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    <title>DEV Community: Hashira Belén Vargas Candia</title>
    <description>The latest articles on DEV Community by Hashira Belén Vargas Candia (@hashiravc).</description>
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      <title>SQL AI Database Solutions: Talking to Databases with Artificial Intelligence</title>
      <dc:creator>Hashira Belén Vargas Candia</dc:creator>
      <pubDate>Sun, 05 Jul 2026 04:55:15 +0000</pubDate>
      <link>https://dev.to/hashiravc/sql-ai-database-solutions-talking-to-databases-with-artificial-intelligence-12ec</link>
      <guid>https://dev.to/hashiravc/sql-ai-database-solutions-talking-to-databases-with-artificial-intelligence-12ec</guid>
      <description>&lt;p&gt;&lt;strong&gt;Public example repository:&lt;/strong&gt; &lt;a href="https://github.com/Hashiravc/text-to-sql-ai" rel="noopener noreferrer"&gt;https://github.com/Hashiravc/text-to-sql-ai&lt;/a&gt;&lt;/p&gt;

&lt;h2&gt;
  
  
  Abstract
&lt;/h2&gt;

&lt;p&gt;&lt;strong&gt;SQL AI Database Solutions&lt;/strong&gt; allow users to ask questions in natural language and receive answers from a database without manually writing SQL. The idea sounds simple: the user asks a question, an AI model generates a SQL query, and the application executes it. In a real-world system, however, generating SQL is not enough. The application must understand the database schema, validate the generated query, restrict permissions, and return reliable results. This article explains a practical Text-to-SQL architecture using Python, SQLite, Streamlit-style examples, and a realistic sales and customer support scenario.&lt;/p&gt;

&lt;h2&gt;
  
  
  1. Why Text-to-SQL Matters
&lt;/h2&gt;

&lt;p&gt;Many organizations store valuable information in relational databases: sales, customers, products, payments, inventory, attendance, support tickets, or academic records. The challenge is that not every user knows SQL. A manager, for example, may want to ask:&lt;/p&gt;

&lt;blockquote&gt;
&lt;p&gt;Which customers have unpaid invoices greater than 500?&lt;/p&gt;
&lt;/blockquote&gt;

&lt;p&gt;A data analyst could solve that with &lt;code&gt;JOIN&lt;/code&gt;, &lt;code&gt;GROUP BY&lt;/code&gt;, and filters. A SQL AI solution tries to convert that business question into a correct SQL query and run it against the database.&lt;/p&gt;

&lt;p&gt;The freeCodeCamp reference presents this idea as an AI-powered data extractor: a user writes a question, and the system uses AI to query a database. Hugging Face also highlights an important warning: Text-to-SQL should not be treated as a simple translation task, because a generated query can be wrong and still return results that look valid. That is why real applications need validation, restrictions, and sometimes an agent that can inspect and improve the output.&lt;/p&gt;

&lt;h2&gt;
  
  
  2. General Architecture
&lt;/h2&gt;

&lt;p&gt;A real SQL AI application can be organized like this:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;User
  -&amp;gt; Web interface or chat
  -&amp;gt; Database schema reader
  -&amp;gt; Prompt for the AI model
  -&amp;gt; Generated SQL
  -&amp;gt; Security validator
  -&amp;gt; Read-only database connection
  -&amp;gt; Table result or natural-language summary
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;The most important rule is that the model should not invent tables or columns. It needs database context: table names, column names, data types, and relationships.&lt;/p&gt;

&lt;h2&gt;
  
  
  3. Real-World Scenario: Sales and Customer Support
&lt;/h2&gt;

&lt;p&gt;Imagine an online store that stores customers, orders, and payment information. The support team wants to answer questions such as:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Which customers still owe money?&lt;/li&gt;
&lt;li&gt;Which products sold the most this month?&lt;/li&gt;
&lt;li&gt;Which orders were partially paid?&lt;/li&gt;
&lt;li&gt;Which customers purchased more than three times?&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;A minimal database schema could look like this:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight sql"&gt;&lt;code&gt;&lt;span class="k"&gt;CREATE&lt;/span&gt; &lt;span class="k"&gt;TABLE&lt;/span&gt; &lt;span class="n"&gt;customers&lt;/span&gt; &lt;span class="p"&gt;(&lt;/span&gt;
  &lt;span class="n"&gt;id&lt;/span&gt; &lt;span class="nb"&gt;INTEGER&lt;/span&gt; &lt;span class="k"&gt;PRIMARY&lt;/span&gt; &lt;span class="k"&gt;KEY&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="n"&gt;name&lt;/span&gt; &lt;span class="nb"&gt;TEXT&lt;/span&gt; &lt;span class="k"&gt;NOT&lt;/span&gt; &lt;span class="k"&gt;NULL&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="n"&gt;email&lt;/span&gt; &lt;span class="nb"&gt;TEXT&lt;/span&gt; &lt;span class="k"&gt;UNIQUE&lt;/span&gt; &lt;span class="k"&gt;NOT&lt;/span&gt; &lt;span class="k"&gt;NULL&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="n"&gt;country&lt;/span&gt; &lt;span class="nb"&gt;TEXT&lt;/span&gt; &lt;span class="k"&gt;NOT&lt;/span&gt; &lt;span class="k"&gt;NULL&lt;/span&gt;
&lt;span class="p"&gt;);&lt;/span&gt;

&lt;span class="k"&gt;CREATE&lt;/span&gt; &lt;span class="k"&gt;TABLE&lt;/span&gt; &lt;span class="n"&gt;orders&lt;/span&gt; &lt;span class="p"&gt;(&lt;/span&gt;
  &lt;span class="n"&gt;id&lt;/span&gt; &lt;span class="nb"&gt;INTEGER&lt;/span&gt; &lt;span class="k"&gt;PRIMARY&lt;/span&gt; &lt;span class="k"&gt;KEY&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="n"&gt;customer_id&lt;/span&gt; &lt;span class="nb"&gt;INTEGER&lt;/span&gt; &lt;span class="k"&gt;NOT&lt;/span&gt; &lt;span class="k"&gt;NULL&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="n"&gt;order_date&lt;/span&gt; &lt;span class="nb"&gt;TEXT&lt;/span&gt; &lt;span class="k"&gt;NOT&lt;/span&gt; &lt;span class="k"&gt;NULL&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="n"&gt;total&lt;/span&gt; &lt;span class="nb"&gt;REAL&lt;/span&gt; &lt;span class="k"&gt;NOT&lt;/span&gt; &lt;span class="k"&gt;NULL&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="n"&gt;paid&lt;/span&gt; &lt;span class="nb"&gt;REAL&lt;/span&gt; &lt;span class="k"&gt;NOT&lt;/span&gt; &lt;span class="k"&gt;NULL&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="n"&gt;status&lt;/span&gt; &lt;span class="nb"&gt;TEXT&lt;/span&gt; &lt;span class="k"&gt;NOT&lt;/span&gt; &lt;span class="k"&gt;NULL&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="k"&gt;FOREIGN&lt;/span&gt; &lt;span class="k"&gt;KEY&lt;/span&gt; &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;customer_id&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;REFERENCES&lt;/span&gt; &lt;span class="n"&gt;customers&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;id&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="p"&gt;);&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;With that data, a natural-language question like this:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;Which customers have unpaid invoices greater than 500?
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;can be converted into SQL:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight sql"&gt;&lt;code&gt;&lt;span class="k"&gt;SELECT&lt;/span&gt;
  &lt;span class="k"&gt;c&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;name&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="k"&gt;c&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;email&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
  &lt;span class="k"&gt;SUM&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;o&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;total&lt;/span&gt; &lt;span class="o"&gt;-&lt;/span&gt; &lt;span class="n"&gt;o&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;paid&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;AS&lt;/span&gt; &lt;span class="n"&gt;pending_amount&lt;/span&gt;
&lt;span class="k"&gt;FROM&lt;/span&gt; &lt;span class="n"&gt;customers&lt;/span&gt; &lt;span class="k"&gt;c&lt;/span&gt;
&lt;span class="k"&gt;JOIN&lt;/span&gt; &lt;span class="n"&gt;orders&lt;/span&gt; &lt;span class="n"&gt;o&lt;/span&gt; &lt;span class="k"&gt;ON&lt;/span&gt; &lt;span class="n"&gt;o&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;customer_id&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;c&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;id&lt;/span&gt;
&lt;span class="k"&gt;WHERE&lt;/span&gt; &lt;span class="n"&gt;o&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;status&lt;/span&gt; &lt;span class="k"&gt;IN&lt;/span&gt; &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s1"&gt;'pending'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="s1"&gt;'partial'&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="k"&gt;GROUP&lt;/span&gt; &lt;span class="k"&gt;BY&lt;/span&gt; &lt;span class="k"&gt;c&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;id&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="k"&gt;c&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;name&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="k"&gt;c&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;email&lt;/span&gt;
&lt;span class="k"&gt;HAVING&lt;/span&gt; &lt;span class="n"&gt;pending_amount&lt;/span&gt; &lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="mi"&gt;500&lt;/span&gt;
&lt;span class="k"&gt;ORDER&lt;/span&gt; &lt;span class="k"&gt;BY&lt;/span&gt; &lt;span class="n"&gt;pending_amount&lt;/span&gt; &lt;span class="k"&gt;DESC&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;This is where Text-to-SQL becomes useful: the user understands the business question, but may not know the SQL syntax required to answer it.&lt;/p&gt;

&lt;h2&gt;
  
  
  4. Creating a Test Database with Python
&lt;/h2&gt;

&lt;p&gt;The following example creates a SQLite database with customers and orders. It is small, but it represents a realistic sales case.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;sqlite3&lt;/span&gt;

&lt;span class="n"&gt;DB_PATH&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;sales_demo.db&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;

&lt;span class="n"&gt;schema&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;
DROP TABLE IF EXISTS orders;
DROP TABLE IF EXISTS customers;

CREATE TABLE customers (
  id INTEGER PRIMARY KEY,
  name TEXT NOT NULL,
  email TEXT UNIQUE NOT NULL,
  country TEXT NOT NULL
);

CREATE TABLE orders (
  id INTEGER PRIMARY KEY,
  customer_id INTEGER NOT NULL,
  order_date TEXT NOT NULL,
  total REAL NOT NULL,
  paid REAL NOT NULL,
  status TEXT NOT NULL,
  FOREIGN KEY (customer_id) REFERENCES customers(id)
);
&lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;

&lt;span class="n"&gt;customers&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;
    &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Ana Torres&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;ana@example.com&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Peru&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
    &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;2&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Luis Ramos&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;luis@example.com&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Chile&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
    &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;3&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Marta Diaz&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;marta@example.com&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Colombia&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
&lt;span class="p"&gt;]&lt;/span&gt;

&lt;span class="n"&gt;orders&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;
    &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;2026-06-01&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;900.00&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;300.00&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;partial&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
    &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;2&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;2026-06-15&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;150.00&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;150.00&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;paid&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
    &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;3&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mi"&gt;2&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;2026-06-20&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;780.00&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;0.00&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;pending&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
    &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;4&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mi"&gt;3&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;2026-06-22&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;120.00&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;120.00&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;paid&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
&lt;span class="p"&gt;]&lt;/span&gt;

&lt;span class="k"&gt;with&lt;/span&gt; &lt;span class="n"&gt;sqlite3&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;connect&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;DB_PATH&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;conn&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="n"&gt;conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;executescript&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;schema&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;executemany&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;INSERT INTO customers (id, name, email, country) VALUES (?, ?, ?, ?)&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="n"&gt;customers&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;executemany&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
        &lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;
        INSERT INTO orders (id, customer_id, order_date, total, paid, status)
        VALUES (?, ?, ?, ?, ?, ?)
        &lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="n"&gt;orders&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="nf"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Database ready:&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;DB_PATH&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  5. Reading the Database Schema Automatically
&lt;/h2&gt;

&lt;p&gt;Before asking a model to generate SQL, we should provide the real schema. In SQLite, we can read it like this:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;sqlite3&lt;/span&gt;

&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;get_schema&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;db_path&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="k"&gt;with&lt;/span&gt; &lt;span class="n"&gt;sqlite3&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;connect&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;db_path&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;conn&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;tables&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;execute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
            &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;SELECT name FROM sqlite_master WHERE type=&lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="s"&gt;table&lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="s"&gt; ORDER BY name&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
        &lt;span class="p"&gt;).&lt;/span&gt;&lt;span class="nf"&gt;fetchall&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;

        &lt;span class="n"&gt;schema_lines&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;[]&lt;/span&gt;
        &lt;span class="nf"&gt;for &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;table_name&lt;/span&gt;&lt;span class="p"&gt;,)&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="n"&gt;tables&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
            &lt;span class="n"&gt;columns&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;execute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;PRAGMA table_info(&lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;table_name&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;)&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;).&lt;/span&gt;&lt;span class="nf"&gt;fetchall&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
            &lt;span class="n"&gt;schema_lines&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;append&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Table: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;table_name&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="k"&gt;for&lt;/span&gt; &lt;span class="n"&gt;column&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="n"&gt;columns&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                &lt;span class="n"&gt;_&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;name&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;data_type&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;not_null&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;_&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;pk&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;column&lt;/span&gt;
                &lt;span class="n"&gt;required&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;NOT NULL&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt; &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;not_null&lt;/span&gt; &lt;span class="k"&gt;else&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;NULL&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
                &lt;span class="n"&gt;primary_key&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;PRIMARY KEY&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt; &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;pk&lt;/span&gt; &lt;span class="k"&gt;else&lt;/span&gt; &lt;span class="sh"&gt;""&lt;/span&gt;
                &lt;span class="n"&gt;schema_lines&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;append&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;  - &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;name&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;data_type&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt; &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;required&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt; &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;primary_key&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="se"&gt;\n&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;join&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;schema_lines&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="nf"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nf"&gt;get_schema&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;sales_demo.db&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;))&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Expected output:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;Table: customers
  - id: INTEGER NULL PRIMARY KEY
  - name: TEXT NOT NULL
  - email: TEXT NOT NULL
  - country: TEXT NOT NULL
Table: orders
  - id: INTEGER NULL PRIMARY KEY
  - customer_id: INTEGER NOT NULL
  - order_date: TEXT NOT NULL
  - total: REAL NOT NULL
  - paid: REAL NOT NULL
  - status: TEXT NOT NULL
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;This context reduces errors because the model knows that &lt;code&gt;customers.email&lt;/code&gt; exists, but it should not invent a column such as &lt;code&gt;customer_phone&lt;/code&gt; if it is not in the schema.&lt;/p&gt;

&lt;h2&gt;
  
  
  6. Prompting the Model to Generate SQL
&lt;/h2&gt;

&lt;p&gt;The prompt should be direct and include clear rules:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;build_prompt&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;schema&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;question&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;
You are a Text-to-SQL assistant.
Generate one SQLite SELECT query for the user&lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="s"&gt;s question.
Use only the tables and columns listed in the schema.
Do not generate INSERT, UPDATE, DELETE, DROP, ALTER, CREATE, PRAGMA, or ATTACH.
Return only SQL, without markdown.

Schema:
&lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;schema&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;

Question:
&lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;question&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;
&lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;In a real application, the model call can use Hugging Face, OpenAI, Groq, Gemini, Claude, or another provider. The important part is to separate responsibilities:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="n"&gt;schema&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;get_schema&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;sales_demo.db&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="n"&gt;question&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Which customers have unpaid invoices greater than 500?&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
&lt;span class="n"&gt;prompt&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;build_prompt&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;schema&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;question&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="n"&gt;sql_query&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;llm&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;generate&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;prompt&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;  &lt;span class="c1"&gt;# Replace this with your selected AI provider
&lt;/span&gt;&lt;span class="nf"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;sql_query&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  7. Validating Before Execution
&lt;/h2&gt;

&lt;p&gt;AI-generated SQL should never be executed without controls. For a demo, we can use a basic validator:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;is_safe_select&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;sql&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="nb"&gt;bool&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="n"&gt;normalized&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt; &lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;join&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;sql&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;strip&lt;/span&gt;&lt;span class="p"&gt;().&lt;/span&gt;&lt;span class="nf"&gt;lower&lt;/span&gt;&lt;span class="p"&gt;().&lt;/span&gt;&lt;span class="nf"&gt;split&lt;/span&gt;&lt;span class="p"&gt;())&lt;/span&gt;
    &lt;span class="n"&gt;forbidden&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;insert&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;update&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;delete&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;drop&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;alter&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;create&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;replace&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;truncate&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;pragma&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;attach&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;detach&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="p"&gt;]&lt;/span&gt;

    &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="ow"&gt;not&lt;/span&gt; &lt;span class="n"&gt;normalized&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;startswith&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;select &lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="bp"&gt;False&lt;/span&gt;

    &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="ow"&gt;not&lt;/span&gt; &lt;span class="nf"&gt;any&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;word&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="n"&gt;normalized&lt;/span&gt; &lt;span class="k"&gt;for&lt;/span&gt; &lt;span class="n"&gt;word&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="n"&gt;forbidden&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;For production, this should be improved with a SQL parser such as &lt;code&gt;sqlglot&lt;/code&gt;, allowlisted tables, a read-only database user, row limits, and query auditing.&lt;/p&gt;

&lt;h2&gt;
  
  
  8. Executing with Read-Only Permissions
&lt;/h2&gt;

&lt;p&gt;The following example opens SQLite in read-only mode and adds &lt;code&gt;LIMIT 50&lt;/code&gt; if the model did not include one:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;sqlite3&lt;/span&gt;

&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;run_safe_query&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;db_path&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;sql&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="nb"&gt;list&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="nb"&gt;tuple&lt;/span&gt;&lt;span class="p"&gt;]:&lt;/span&gt;
    &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="ow"&gt;not&lt;/span&gt; &lt;span class="nf"&gt;is_safe_select&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;sql&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
        &lt;span class="k"&gt;raise&lt;/span&gt; &lt;span class="nc"&gt;ValueError&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Unsafe SQL generated by model&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="n"&gt;safe_sql&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;sql&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;strip&lt;/span&gt;&lt;span class="p"&gt;().&lt;/span&gt;&lt;span class="nf"&gt;rstrip&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;;&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt; limit &lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt; &lt;span class="ow"&gt;not&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt; &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;safe_sql&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;lower&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt; &lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;safe_sql&lt;/span&gt; &lt;span class="o"&gt;+=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt; LIMIT 50&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;

    &lt;span class="n"&gt;readonly_uri&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;file:&lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;db_path&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;?mode=ro&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
    &lt;span class="k"&gt;with&lt;/span&gt; &lt;span class="n"&gt;sqlite3&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;connect&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;readonly_uri&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;uri&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="bp"&gt;True&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;conn&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="n"&gt;conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;execute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;safe_sql&lt;/span&gt;&lt;span class="p"&gt;).&lt;/span&gt;&lt;span class="nf"&gt;fetchall&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Usage:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="n"&gt;sql_query&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;
SELECT
  c.name,
  c.email,
  SUM(o.total - o.paid) AS pending_amount
FROM customers c
JOIN orders o ON o.customer_id = c.id
WHERE o.status IN (&lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="s"&gt;pending&lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="s"&gt;, &lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="s"&gt;partial&lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="s"&gt;)
GROUP BY c.id, c.name, c.email
HAVING pending_amount &amp;gt; 500
ORDER BY pending_amount DESC
&lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;

&lt;span class="n"&gt;rows&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;run_safe_query&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;sales_demo.db&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;sql_query&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="nf"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;rows&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Possible output:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;[('Luis Ramos', 'luis@example.com', 780.0), ('Ana Torres', 'ana@example.com', 600.0)]
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  9. Mini Interface with Streamlit
&lt;/h2&gt;

&lt;p&gt;A simple interface can display the user question, generated SQL, and database results:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;streamlit&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;st&lt;/span&gt;

&lt;span class="n"&gt;DB_PATH&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;sales_demo.db&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;

&lt;span class="n"&gt;st&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;title&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Text-to-SQL AI Demo&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="n"&gt;question&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;st&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;text_input&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Ask a question about sales&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;st&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;button&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Generate SQL&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="ow"&gt;and&lt;/span&gt; &lt;span class="n"&gt;question&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="n"&gt;schema&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;get_schema&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;DB_PATH&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;prompt&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;build_prompt&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;schema&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;question&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="n"&gt;sql_query&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;llm&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;generate&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;prompt&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;st&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;code&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;sql_query&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;language&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;sql&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="k"&gt;try&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;rows&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;run_safe_query&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;DB_PATH&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;sql_query&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;st&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;write&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;rows&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="k"&gt;except&lt;/span&gt; &lt;span class="nb"&gt;Exception&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;error&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;st&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;error&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Could not execute the query: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;error&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;This flow matches the idea from the Medium reference: a lightweight Streamlit app, a SQLite database, and a model call. The key improvement here is that we add validation and dynamic schema reading instead of depending only on a fixed prompt.&lt;/p&gt;

&lt;h2&gt;
  
  
  10. Agent-Based Approach
&lt;/h2&gt;

&lt;p&gt;Hugging Face shows another useful improvement: using an agent with a SQL tool. The tool contains the table description, and the agent can iterate if it needs to correct the query.&lt;/p&gt;

&lt;p&gt;A conceptual example with &lt;code&gt;smolagents&lt;/code&gt; looks like this:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;sqlalchemy&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;create_engine&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;inspect&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;text&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;smolagents&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;CodeAgent&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;InferenceClientModel&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;tool&lt;/span&gt;

&lt;span class="n"&gt;engine&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;create_engine&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;sqlite:///sales_demo.db&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;describe_tables&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="n"&gt;inspector&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;inspect&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;engine&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;description&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;[]&lt;/span&gt;
    &lt;span class="k"&gt;for&lt;/span&gt; &lt;span class="n"&gt;table&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="n"&gt;inspector&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get_table_names&lt;/span&gt;&lt;span class="p"&gt;():&lt;/span&gt;
        &lt;span class="n"&gt;columns&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;inspector&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get_columns&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;table&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;description&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;append&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Table &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;table&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;:&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="k"&gt;for&lt;/span&gt; &lt;span class="n"&gt;column&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="n"&gt;columns&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
            &lt;span class="n"&gt;description&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;append&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;  - &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;column&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="s"&gt;name&lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;column&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="s"&gt;type&lt;/span&gt;&lt;span class="sh"&gt;'&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="se"&gt;\n&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;join&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;description&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="nd"&gt;@tool&lt;/span&gt;
&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;sql_engine&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;query&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;
    Execute a read-only SQL query over the sales database.

    Args:
        query: A safe SQLite SELECT query.
    &lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;
    &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="ow"&gt;not&lt;/span&gt; &lt;span class="nf"&gt;is_safe_select&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;query&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Rejected: only safe SELECT queries are allowed.&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;

    &lt;span class="k"&gt;with&lt;/span&gt; &lt;span class="n"&gt;engine&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;connect&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;connection&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;rows&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;connection&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;execute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nf"&gt;text&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;query&lt;/span&gt;&lt;span class="p"&gt;)).&lt;/span&gt;&lt;span class="nf"&gt;fetchall&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
    &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="se"&gt;\n&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;join&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nf"&gt;str&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;row&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;for&lt;/span&gt; &lt;span class="n"&gt;row&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="n"&gt;rows&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="n"&gt;sql_engine&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;description&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;
Use this tool to answer business questions with SQL.
Available schema:
&lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="nf"&gt;describe_tables&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;
&lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;

&lt;span class="n"&gt;agent&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;CodeAgent&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
    &lt;span class="n"&gt;tools&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;sql_engine&lt;/span&gt;&lt;span class="p"&gt;],&lt;/span&gt;
    &lt;span class="n"&gt;model&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="nc"&gt;InferenceClientModel&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;model_id&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;meta-llama/Llama-3.1-8B-Instruct&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="n"&gt;agent&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;run&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Which customers have pending debt greater than 500?&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;This approach is useful when the database has multiple tables and the model needs to reason about joins. Even then, the agent should use a safe tool, not a full-permission database connection.&lt;/p&gt;

&lt;h2&gt;
  
  
  11. Best Practices for Real Projects
&lt;/h2&gt;

&lt;ol&gt;
&lt;li&gt;Use a read-only database user.&lt;/li&gt;
&lt;li&gt;Send only the required schema to the model, not sensitive data.&lt;/li&gt;
&lt;li&gt;Validate generated SQL with a parser, not only with string checks.&lt;/li&gt;
&lt;li&gt;Block dangerous statements such as &lt;code&gt;DROP&lt;/code&gt;, &lt;code&gt;DELETE&lt;/code&gt;, &lt;code&gt;UPDATE&lt;/code&gt;, or &lt;code&gt;ALTER&lt;/code&gt;.&lt;/li&gt;
&lt;li&gt;Add a default &lt;code&gt;LIMIT&lt;/code&gt; to avoid large accidental queries.&lt;/li&gt;
&lt;li&gt;Log the user question, generated SQL, execution time, and errors.&lt;/li&gt;
&lt;li&gt;Show the generated SQL to the user for transparency.&lt;/li&gt;
&lt;li&gt;Require human confirmation in sensitive domains such as health, finance, or personal data.&lt;/li&gt;
&lt;li&gt;Evaluate the system with real business questions.&lt;/li&gt;
&lt;li&gt;Measure accuracy: a query that runs successfully is not always correct.&lt;/li&gt;
&lt;/ol&gt;

&lt;h2&gt;
  
  
  12. Important Observation
&lt;/h2&gt;

&lt;p&gt;The hardest part of a SQL AI solution is not connecting the model. The hardest part is building trust. A model can generate a query that runs without errors but answers the wrong question. For example, it may forget a date filter, use the wrong column, or create a &lt;code&gt;JOIN&lt;/code&gt; that duplicates totals. This is why the architecture should include validation, tests with known questions, and human review for critical reports.&lt;/p&gt;

&lt;h2&gt;
  
  
  Conclusion
&lt;/h2&gt;

&lt;p&gt;SQL AI Database Solutions make databases more accessible. They allow non-technical users to ask business questions in natural language and receive answers from real data. However, the solution must be designed carefully: schema context, validation, read-only permissions, limits, and monitoring are required. AI does not replace the judgment of a developer or analyst; it amplifies it when integrated with good engineering practices.&lt;/p&gt;

&lt;p&gt;In short: Text-to-SQL is powerful, but it should be treated as an assisted query tool, not as an unrestricted door into the database.&lt;/p&gt;

&lt;h2&gt;
  
  
  References
&lt;/h2&gt;

&lt;ul&gt;
&lt;li&gt;freeCodeCamp: &lt;a href="https://www.freecodecamp.org/news/talk-to-databases-using-ai-build-a-sql-query-data-extractor" rel="noopener noreferrer"&gt;How to Talk to Any Database Using AI - Build Your Own SQL Query Data Extractor&lt;/a&gt;
&lt;/li&gt;
&lt;li&gt;Hugging Face: &lt;a href="https://huggingface.co/docs/smolagents/examples/text_to_sql" rel="noopener noreferrer"&gt;Text-to-SQL with smolagents&lt;/a&gt;
&lt;/li&gt;
&lt;li&gt;Medium: &lt;a href="https://medium.com/@kuhelidey878/building-a-text-to-sql-query-generator-with-streamlit-and-hugging-face-turn-natural-language-into-3e81eee198fb" rel="noopener noreferrer"&gt;Building a Text-to-SQL Query Generator with Streamlit and Hugging Face&lt;/a&gt;
&lt;/li&gt;
&lt;/ul&gt;

</description>
    </item>
    <item>
      <title>Practical Modern Observability: FastAPI, OpenTelemetry, Prometheus, Jaeger, and Grafana</title>
      <dc:creator>Hashira Belén Vargas Candia</dc:creator>
      <pubDate>Wed, 01 Jul 2026 06:38:56 +0000</pubDate>
      <link>https://dev.to/hashiravc/practical-modern-observability-fastapi-opentelemetry-prometheus-jaeger-and-grafana-46bj</link>
      <guid>https://dev.to/hashiravc/practical-modern-observability-fastapi-opentelemetry-prometheus-jaeger-and-grafana-46bj</guid>
      <description>&lt;p&gt;In modern, distributed architectures (like microservices or serverless applications), understanding why a system failed or why it is running slowly is a massive engineering challenge. &lt;/p&gt;

&lt;p&gt;When a user complains that a checkout operation failed, you cannot simply look at a single server’s log file. That request may have traversed a Gateway, an Order service, a Payment processor, an Inventory system, and a database. You need a way to correlate all of these events across network and process boundaries.&lt;/p&gt;

&lt;p&gt;This is where &lt;strong&gt;Observability&lt;/strong&gt; comes in.&lt;/p&gt;

&lt;p&gt;In this article, we will cover the core concepts of modern observability practices, explain the OpenTelemetry standard, and walk through a complete, real-world Python implementation. We will build a containerized FastAPI application instrumented with &lt;strong&gt;OpenTelemetry&lt;/strong&gt; that exports metrics to &lt;strong&gt;Prometheus&lt;/strong&gt;, sends traces to &lt;strong&gt;Jaeger&lt;/strong&gt;, and compiles everything into a unified &lt;strong&gt;Grafana&lt;/strong&gt; dashboard.&lt;/p&gt;




&lt;h3&gt;
  
  
  Repository: &lt;a href="https://github.com/Hashiravc/Observability-Practices.git" rel="noopener noreferrer"&gt;https://github.com/Hashiravc/Observability-Practices.git&lt;/a&gt;
&lt;/h3&gt;

&lt;h2&gt;
  
  
  1. What is Observability?
&lt;/h2&gt;

&lt;p&gt;Often confused with monitoring, &lt;strong&gt;observability&lt;/strong&gt; is the measure of how well you can infer the internal states of a system based on its external outputs.&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;  &lt;strong&gt;Monitoring&lt;/strong&gt; tells you &lt;em&gt;when&lt;/em&gt; a system is broken (e.g., "CPU usage is 99%" or "HTTP 500 error rate is &amp;gt; 5%"). It is about tracking pre-defined metrics.&lt;/li&gt;
&lt;li&gt;  &lt;strong&gt;Observability&lt;/strong&gt; tells you &lt;em&gt;why&lt;/em&gt; it is broken (e.g., "The payment service is slow because database query &lt;code&gt;SELECT * FROM payment_methods&lt;/code&gt; took 3 seconds under a specific trace context"). It is about asking questions you didn't anticipate.&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;To achieve observability, we rely on the &lt;strong&gt;three pillars of telemetry&lt;/strong&gt;:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt; &lt;strong&gt;Metrics&lt;/strong&gt;: Structured, aggregated numerical data that track resource usage or business KPIs over time. (e.g., CPU load, request count, revenue). Metrics are ideal for alerting.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Traces&lt;/strong&gt;: Represent the end-to-end journey of a request as it flows through a distributed system. A trace is composed of one or more &lt;strong&gt;spans&lt;/strong&gt; (individual units of work). Traces are crucial for isolating latency bottlenecks and database serialization errors.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Logs&lt;/strong&gt;: Timestamped, text-based entries describing specific, discrete events. In highly observable systems, logs are &lt;strong&gt;structured&lt;/strong&gt; (JSON-formatted) and inject trace IDs to correlate logs directly with traces.&lt;/li&gt;
&lt;/ol&gt;




&lt;h2&gt;
  
  
  2. The OpenTelemetry Standard
&lt;/h2&gt;

&lt;p&gt;Historically, implementing observability meant using proprietary libraries from vendor platforms (like Datadog, New Relic, or Dynatrace). If you wanted to change platforms, you had to rewrite your application instrumentation.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;OpenTelemetry (OTel)&lt;/strong&gt; is an open-source, vendor-neutral collection of APIs, SDKs, and tools hosted by the Cloud Native Computing Foundation (CNCF). It provides a single standard for gathering metrics, logs, and traces. &lt;/p&gt;

&lt;p&gt;By instrumenting your code with the OpenTelemetry API, you can swap out telemetry backends (e.g., from local Prometheus/Jaeger to Datadog or AWS CloudWatch) by changing simple configuration variables—&lt;strong&gt;without modifying a single line of application code&lt;/strong&gt;.&lt;/p&gt;




&lt;h2&gt;
  
  
  3. Demo Application Architecture
&lt;/h2&gt;

&lt;p&gt;To demonstrate observability practices in a real-world scenario, we will build a containerized E-Commerce application with the following architecture:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;  [ Traffic Generator ]
           │
           ▼ (HTTP request)
     [ FastAPI Web ] ──────────────► [ SQLite DB ]
           │ (Exposes /metrics)
           ├───────────────────────► [ Prometheus ] ──────┐
           │                                              ▼
           ├─► (OTLP Traces gRPC) ──► [ Jaeger ] ────► [ Grafana Dashboard ]
           │
        (W3C Trace Headers)
           │
           ▼
   [ /inventory/deduct ]
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;When a client hits &lt;code&gt;/checkout&lt;/code&gt;:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt; A parent span &lt;code&gt;checkout_transaction&lt;/code&gt; is created.&lt;/li&gt;
&lt;li&gt; A database entry is written inside a child span (&lt;code&gt;db_create_order&lt;/code&gt;).&lt;/li&gt;
&lt;li&gt; An HTTP request is made to the &lt;code&gt;/inventory/deduct&lt;/code&gt; route. To trace this across network boundaries, we manually inject &lt;strong&gt;W3C Trace Context&lt;/strong&gt; headers.&lt;/li&gt;
&lt;li&gt; The inventory service extracts the context and begins a child span &lt;code&gt;inventory_deduct_span&lt;/code&gt; to deduct item stock.&lt;/li&gt;
&lt;li&gt; If we request checkout of specific items, we simulate network latency (sleep) or write lock deadlocks (500 errors).&lt;/li&gt;
&lt;/ol&gt;




&lt;h2&gt;
  
  
  4. Code Walkthrough
&lt;/h2&gt;

&lt;p&gt;Let us look at how this is implemented.&lt;/p&gt;

&lt;h3&gt;
  
  
  Dependency Configuration (&lt;code&gt;requirements.txt&lt;/code&gt;)
&lt;/h3&gt;

&lt;p&gt;We install FastAPI, Uvicorn, SQLAlchemy, and the official OpenTelemetry SDK packages, including the Prometheus metric reader and OTLP trace exporter:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;fastapi==0.111.0
uvicorn==0.30.1
sqlalchemy==2.0.31
httpx==0.27.0
prometheus-client==0.20.0
opentelemetry-api==1.25.0
opentelemetry-sdk==1.25.0
opentelemetry-instrumentation-fastapi==0.46b0
opentelemetry-exporter-otlp==1.25.0
opentelemetry-exporter-prometheus==1.25.0
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  Telemetry Configuration (&lt;code&gt;app/telemetry.py&lt;/code&gt;)
&lt;/h3&gt;

&lt;p&gt;This file initializes OpenTelemetry, registers exporters, and defines custom application-level metrics.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;os&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;fastapi&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;FastAPI&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;trace&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;metrics&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry.sdk.trace&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;TracerProvider&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry.sdk.trace.export&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;BatchSpanProcessor&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;ConsoleSpanExporter&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry.exporter.otlp.proto.grpc.trace_exporter&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;OTLPSpanExporter&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry.sdk.metrics&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;MeterProvider&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry.exporter.prometheus&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;PrometheusMetricReader&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry.sdk.resources&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;Resource&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;SERVICE_NAME&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry.instrumentation.fastapi&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;FastAPIInstrumentor&lt;/span&gt;

&lt;span class="c1"&gt;# Define service metadata
&lt;/span&gt;&lt;span class="n"&gt;SERVICE_NAME_VALUE&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;os&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;getenv&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;OTEL_SERVICE_NAME&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order-service&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="n"&gt;resource&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;Resource&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;create&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt;&lt;span class="n"&gt;SERVICE_NAME&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;SERVICE_NAME_VALUE&lt;/span&gt;&lt;span class="p"&gt;})&lt;/span&gt;

&lt;span class="c1"&gt;# 1. Tracing Setup
&lt;/span&gt;&lt;span class="n"&gt;tracer_provider&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;TracerProvider&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;resource&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;resource&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="c1"&gt;# Configure OTLP Exporter (sending traces to Jaeger via gRPC)
&lt;/span&gt;&lt;span class="n"&gt;otlp_endpoint&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;os&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;getenv&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;OTEL_EXPORTER_OTLP_ENDPOINT&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;http://localhost:4317&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="k"&gt;try&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="n"&gt;otlp_exporter&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;OTLPSpanExporter&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;endpoint&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;otlp_endpoint&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;insecure&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="bp"&gt;True&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;span_processor&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;BatchSpanProcessor&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;otlp_exporter&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;tracer_provider&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;add_span_processor&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;span_processor&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="k"&gt;except&lt;/span&gt; &lt;span class="nb"&gt;Exception&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;e&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="nf"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Could not initialize OTLP exporter: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;e&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;. Falling back to console.&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;console_exporter&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;ConsoleSpanExporter&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
    &lt;span class="n"&gt;span_processor&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;BatchSpanProcessor&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;console_exporter&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;tracer_provider&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;add_span_processor&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;span_processor&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="n"&gt;trace&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_tracer_provider&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;tracer_provider&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="n"&gt;tracer&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;trace&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get_tracer&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order-service-tracer&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="c1"&gt;# 2. Metrics Setup (Prometheus Pull Exporter)
&lt;/span&gt;&lt;span class="n"&gt;prometheus_reader&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;PrometheusMetricReader&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;span class="n"&gt;meter_provider&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;MeterProvider&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;resource&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;resource&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;metric_readers&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;prometheus_reader&lt;/span&gt;&lt;span class="p"&gt;])&lt;/span&gt;
&lt;span class="n"&gt;metrics&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_meter_provider&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;meter_provider&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="n"&gt;meter&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;metrics&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get_meter&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order-service-meter&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="c1"&gt;# Custom business and performance metrics
&lt;/span&gt;&lt;span class="n"&gt;checkout_counter&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;meter&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;create_counter&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
    &lt;span class="n"&gt;name&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order_checkouts_total&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="n"&gt;description&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Total number of checkout requests processed&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="n"&gt;unit&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;1&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="n"&gt;revenue_counter&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;meter&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;create_counter&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
    &lt;span class="n"&gt;name&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order_revenue_total&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="n"&gt;description&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Total revenue generated from checkouts&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="n"&gt;unit&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;USD&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="n"&gt;checkout_errors&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;meter&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;create_counter&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
    &lt;span class="n"&gt;name&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order_checkout_errors_total&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="n"&gt;description&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Total failed checkouts&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="n"&gt;unit&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;1&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;setup_telemetry&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;app&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;FastAPI&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
    &lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;
    Instruments the FastAPI application.
    &lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;
    &lt;span class="c1"&gt;# Auto-instrumentation hooks FastAPI request durations and details
&lt;/span&gt;    &lt;span class="n"&gt;FastAPIInstrumentor&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;instrument_app&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
        &lt;span class="n"&gt;app&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="n"&gt;tracer_provider&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;tracer_provider&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="n"&gt;meter_provider&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;meter_provider&lt;/span&gt;
    &lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  Application Implementation (&lt;code&gt;app/main.py&lt;/code&gt;)
&lt;/h3&gt;

&lt;p&gt;Here we set up our FastAPI endpoints. Notice how trace context is injected on &lt;code&gt;/checkout&lt;/code&gt; and extracted on &lt;code&gt;/inventory/deduct&lt;/code&gt; using W3C Trace Context propagation.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;os&lt;/span&gt;
&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;time&lt;/span&gt;
&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;random&lt;/span&gt;
&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;httpx&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;fastapi&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;FastAPI&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;Depends&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;HTTPException&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;Header&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;Response&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;Request&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;pydantic&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;BaseModel&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;sqlalchemy.orm&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;Session&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;prometheus_client&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;generate_latest&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;CONTENT_TYPE_LATEST&lt;/span&gt;

&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;app.database&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;init_db&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;get_db&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;Inventory&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;app.telemetry&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="p"&gt;(&lt;/span&gt;
    &lt;span class="n"&gt;setup_telemetry&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="n"&gt;tracer&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="n"&gt;checkout_counter&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="n"&gt;revenue_counter&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="n"&gt;checkout_errors&lt;/span&gt;
&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;trace&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry.trace.propagation.tracecontext&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;TraceContextTextMapPropagator&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;opentelemetry.trace&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;StatusCode&lt;/span&gt;

&lt;span class="n"&gt;app&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;FastAPI&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;title&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;E-Commerce Observability Demo API&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="nf"&gt;setup_telemetry&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;app&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="n"&gt;INVENTORY_URL&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;os&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;getenv&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;INVENTORY_URL&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;http://localhost:8000&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

&lt;span class="k"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;CheckoutRequest&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;BaseModel&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
    &lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;
    &lt;span class="n"&gt;quantity&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;int&lt;/span&gt;
    &lt;span class="n"&gt;price&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;float&lt;/span&gt;

&lt;span class="k"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;InventoryDeductRequest&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;BaseModel&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
    &lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;
    &lt;span class="n"&gt;quantity&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;int&lt;/span&gt;

&lt;span class="nd"&gt;@app.on_event&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;startup&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;on_startup&lt;/span&gt;&lt;span class="p"&gt;():&lt;/span&gt;
    &lt;span class="nf"&gt;init_db&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;

&lt;span class="nd"&gt;@app.get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;/&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;home&lt;/span&gt;&lt;span class="p"&gt;():&lt;/span&gt;
    &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;message&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Welcome to the E-Commerce Observability Demo API!&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;

&lt;span class="nd"&gt;@app.post&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;/checkout&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;checkout&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;CheckoutRequest&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;db&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;Session&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;Depends&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;get_db&lt;/span&gt;&lt;span class="p"&gt;)):&lt;/span&gt;
    &lt;span class="n"&gt;checkout_counter&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;item&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;})&lt;/span&gt;

    &lt;span class="c1"&gt;# Start parent trace span
&lt;/span&gt;    &lt;span class="k"&gt;with&lt;/span&gt; &lt;span class="n"&gt;tracer&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;start_as_current_span&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;checkout_transaction&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_attribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order.item&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_attribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order.quantity&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_attribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order.price_per_unit&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;price&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

        &lt;span class="c1"&gt;# Child database span
&lt;/span&gt;        &lt;span class="k"&gt;with&lt;/span&gt; &lt;span class="n"&gt;tracer&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;start_as_current_span&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;db_create_order&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;db_span&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
            &lt;span class="n"&gt;db_order&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
                &lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                &lt;span class="n"&gt;quantity&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                &lt;span class="n"&gt;price&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;price&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                &lt;span class="n"&gt;status&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;PENDING&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
            &lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="n"&gt;db&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;db_order&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="n"&gt;db&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;commit&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
            &lt;span class="n"&gt;db&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;refresh&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;db_order&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="n"&gt;db_span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_attribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;db.order_id&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;db_order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nb"&gt;id&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="n"&gt;order_id&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;db_order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nb"&gt;id&lt;/span&gt;

        &lt;span class="c1"&gt;# Downstream HTTP client span + Trace context injection
&lt;/span&gt;        &lt;span class="n"&gt;headers&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{}&lt;/span&gt;
        &lt;span class="nc"&gt;TraceContextTextMapPropagator&lt;/span&gt;&lt;span class="p"&gt;().&lt;/span&gt;&lt;span class="nf"&gt;inject&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;headers&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="c1"&gt;# Injects 'traceparent' header
&lt;/span&gt;
        &lt;span class="k"&gt;with&lt;/span&gt; &lt;span class="n"&gt;tracer&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;start_as_current_span&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;http_call_inventory_service&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;http_span&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
            &lt;span class="n"&gt;http_span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_attribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;http.url&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;INVENTORY_URL&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;/inventory/deduct&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="k"&gt;try&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                &lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="k"&gt;with&lt;/span&gt; &lt;span class="n"&gt;httpx&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nc"&gt;AsyncClient&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;client&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                    &lt;span class="n"&gt;response&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="n"&gt;client&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;post&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
                        &lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;INVENTORY_URL&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt;/inventory/deduct&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                        &lt;span class="n"&gt;json&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;item&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;quantity&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt;&lt;span class="p"&gt;},&lt;/span&gt;
                        &lt;span class="n"&gt;headers&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;headers&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                        &lt;span class="n"&gt;timeout&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="mf"&gt;5.0&lt;/span&gt;
                    &lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="k"&gt;except&lt;/span&gt; &lt;span class="nb"&gt;Exception&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;exc&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                &lt;span class="n"&gt;checkout_errors&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;item&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;reason&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;inventory_network_error&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;})&lt;/span&gt;
                &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_status&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;StatusCode&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;ERROR&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Inventory communication failed: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;exc&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
                &lt;span class="n"&gt;http_span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;record_exception&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;exc&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
                &lt;span class="n"&gt;db_order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;status&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;FAILED&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
                &lt;span class="n"&gt;db&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;commit&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
                &lt;span class="k"&gt;raise&lt;/span&gt; &lt;span class="nc"&gt;HTTPException&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;status_code&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="mi"&gt;502&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;detail&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Inventory service network error&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

            &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;response&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;status_code&lt;/span&gt; &lt;span class="o"&gt;!=&lt;/span&gt; &lt;span class="mi"&gt;200&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                &lt;span class="n"&gt;checkout_errors&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;item&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;reason&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;inventory_rejection&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;})&lt;/span&gt;
                &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_status&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;StatusCode&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;ERROR&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Inventory check rejected: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;response&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;text&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
                &lt;span class="n"&gt;db_order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;status&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;FAILED&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
                &lt;span class="n"&gt;db&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;commit&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
                &lt;span class="k"&gt;raise&lt;/span&gt; &lt;span class="nc"&gt;HTTPException&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;status_code&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;response&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;status_code&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;detail&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Inventory deduction rejected: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;response&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;text&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

        &lt;span class="c1"&gt;# Success path
&lt;/span&gt;        &lt;span class="n"&gt;db_order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;status&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;COMPLETED&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
        &lt;span class="n"&gt;db&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;commit&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;

        &lt;span class="n"&gt;total_revenue&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt; &lt;span class="o"&gt;*&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;price&lt;/span&gt;
        &lt;span class="n"&gt;revenue_counter&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;total_revenue&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;item&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;})&lt;/span&gt;
        &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_attribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order.status&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;COMPLETED&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_attribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order.revenue&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;total_revenue&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;order_id&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;status&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;COMPLETED&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;item&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;total_price&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;total_revenue&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;

&lt;span class="nd"&gt;@app.post&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;/inventory/deduct&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;deduct_inventory&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;InventoryDeductRequest&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;request&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;Request&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;db&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;Session&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;Depends&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;get_db&lt;/span&gt;&lt;span class="p"&gt;)):&lt;/span&gt;
    &lt;span class="c1"&gt;# Extract trace parent header from HTTP client call
&lt;/span&gt;    &lt;span class="n"&gt;carrier&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;traceparent&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;request&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;headers&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;traceparent&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;""&lt;/span&gt;&lt;span class="p"&gt;)}&lt;/span&gt;
    &lt;span class="n"&gt;extracted_context&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;TraceContextTextMapPropagator&lt;/span&gt;&lt;span class="p"&gt;().&lt;/span&gt;&lt;span class="nf"&gt;extract&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;carrier&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;carrier&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="k"&gt;with&lt;/span&gt; &lt;span class="n"&gt;tracer&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;start_as_current_span&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;inventory_deduct_span&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;context&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;extracted_context&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_attribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;inventory.item&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_attribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;inventory.deduction_quantity&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

        &lt;span class="c1"&gt;# Simulate network latency (2 seconds) for large smartphone orders
&lt;/span&gt;        &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt; &lt;span class="o"&gt;==&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;smartphone&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt; &lt;span class="ow"&gt;and&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt; &lt;span class="o"&gt;&amp;gt;=&lt;/span&gt; &lt;span class="mi"&gt;3&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
            &lt;span class="n"&gt;delay&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;random&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;uniform&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mf"&gt;1.0&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;2.5&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_attribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;simulation.latency_added&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;delay&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="n"&gt;time&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;sleep&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;delay&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

        &lt;span class="c1"&gt;# Simulate db locks/deadlock conflicts (500 Server Error) for large laptop orders
&lt;/span&gt;        &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt; &lt;span class="o"&gt;==&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;laptop&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt; &lt;span class="ow"&gt;and&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt; &lt;span class="o"&gt;&amp;gt;=&lt;/span&gt; &lt;span class="mi"&gt;2&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
            &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;random&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;random&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;&amp;lt;&lt;/span&gt; &lt;span class="mf"&gt;0.6&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_status&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;StatusCode&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;ERROR&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Simulated deadlock conflict&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
                &lt;span class="k"&gt;raise&lt;/span&gt; &lt;span class="nc"&gt;HTTPException&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;status_code&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="mi"&gt;500&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;detail&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Database deadlock conflict during write&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

        &lt;span class="n"&gt;db_item&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;db&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;query&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;Inventory&lt;/span&gt;&lt;span class="p"&gt;).&lt;/span&gt;&lt;span class="nf"&gt;filter&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;Inventory&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt; &lt;span class="o"&gt;==&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;item&lt;/span&gt;&lt;span class="p"&gt;).&lt;/span&gt;&lt;span class="nf"&gt;first&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
        &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="ow"&gt;not&lt;/span&gt; &lt;span class="n"&gt;db_item&lt;/span&gt; &lt;span class="ow"&gt;or&lt;/span&gt; &lt;span class="n"&gt;db_item&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt; &lt;span class="o"&gt;&amp;lt;&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
            &lt;span class="n"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set_status&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;StatusCode&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;ERROR&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Insufficient stock&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="k"&gt;raise&lt;/span&gt; &lt;span class="nc"&gt;HTTPException&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;status_code&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="mi"&gt;400&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;detail&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Insufficient stock&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

        &lt;span class="n"&gt;db_item&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt; &lt;span class="o"&gt;-=&lt;/span&gt; &lt;span class="n"&gt;request_data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt;
        &lt;span class="n"&gt;db&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;commit&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;status&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;SUCCESS&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;remaining_stock&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;db_item&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;quantity&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;

&lt;span class="nd"&gt;@app.get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;/metrics&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;metrics_endpoint&lt;/span&gt;&lt;span class="p"&gt;():&lt;/span&gt;
    &lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;
    Exposes metrics scraped by Prometheus server.
    &lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;
    &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nc"&gt;Response&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nf"&gt;generate_latest&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt; &lt;span class="n"&gt;media_type&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;CONTENT_TYPE_LATEST&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;






&lt;h2&gt;
  
  
  5. Orchestrating the Stack with Docker Compose
&lt;/h2&gt;

&lt;p&gt;To run this observability stack locally, we define a multi-container deployment using Docker Compose. We launch:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt; Our &lt;strong&gt;FastAPI App&lt;/strong&gt; on port &lt;code&gt;8000&lt;/code&gt;.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Prometheus&lt;/strong&gt; on port &lt;code&gt;9090&lt;/code&gt; to collect the metric endpoints.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Jaeger&lt;/strong&gt; on port &lt;code&gt;16686&lt;/code&gt; (Web UI) and &lt;code&gt;4317&lt;/code&gt; (gRPC collector) to receive tracing spans.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Grafana&lt;/strong&gt; on port &lt;code&gt;3000&lt;/code&gt; to aggregate datasources.&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;Here is the &lt;code&gt;docker-compose.yml&lt;/code&gt; config:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight yaml"&gt;&lt;code&gt;&lt;span class="na"&gt;version&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;"&lt;/span&gt;&lt;span class="s"&gt;3.8"&lt;/span&gt;

&lt;span class="na"&gt;services&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
  &lt;span class="na"&gt;web&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
    &lt;span class="na"&gt;build&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;.&lt;/span&gt;
    &lt;span class="na"&gt;ports&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s2"&gt;"&lt;/span&gt;&lt;span class="s"&gt;8000:8000"&lt;/span&gt;
    &lt;span class="na"&gt;environment&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;OTEL_SERVICE_NAME=order-service&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;OTEL_EXPORTER_OTLP_ENDPOINT=http://jaeger:4317&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;INVENTORY_URL=http://web:8000&lt;/span&gt;
    &lt;span class="na"&gt;depends_on&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;jaeger&lt;/span&gt;

  &lt;span class="na"&gt;jaeger&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
    &lt;span class="na"&gt;image&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;jaegertracing/all-in-one:1.57&lt;/span&gt;
    &lt;span class="na"&gt;ports&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s2"&gt;"&lt;/span&gt;&lt;span class="s"&gt;16686:16686"&lt;/span&gt; &lt;span class="c1"&gt;# Web UI&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s2"&gt;"&lt;/span&gt;&lt;span class="s"&gt;4317:4317"&lt;/span&gt;   &lt;span class="c1"&gt;# OTLP gRPC receiver&lt;/span&gt;
    &lt;span class="na"&gt;environment&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;COLLECTOR_OTLP_ENABLED=true&lt;/span&gt;

  &lt;span class="na"&gt;prometheus&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
    &lt;span class="na"&gt;image&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;prom/prometheus:v2.52.0&lt;/span&gt;
    &lt;span class="na"&gt;volumes&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;./prometheus.yml:/etc/prometheus/prometheus.yml&lt;/span&gt;
    &lt;span class="na"&gt;ports&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s2"&gt;"&lt;/span&gt;&lt;span class="s"&gt;9090:9090"&lt;/span&gt;

  &lt;span class="na"&gt;grafana&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
    &lt;span class="na"&gt;image&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;grafana/grafana:11.0.0&lt;/span&gt;
    &lt;span class="na"&gt;volumes&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;./grafana/provisioning:/etc/grafana/provisioning&lt;/span&gt;
    &lt;span class="na"&gt;ports&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s2"&gt;"&lt;/span&gt;&lt;span class="s"&gt;3000:3000"&lt;/span&gt;
    &lt;span class="na"&gt;environment&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;GF_AUTH_ANONYMOUS_ENABLED=true&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;GF_AUTH_ANONYMOUS_ORG_ROLE=Admin&lt;/span&gt;
    &lt;span class="na"&gt;depends_on&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;prometheus&lt;/span&gt;
      &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="s"&gt;jaeger&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;






&lt;h2&gt;
  
  
  6. How it Looks in Action
&lt;/h2&gt;

&lt;p&gt;When you run &lt;code&gt;docker compose up --build&lt;/code&gt;, start the traffic generator (&lt;code&gt;generate_traffic.py&lt;/code&gt;), and log in to Grafana, you will see a unified, correlated interface.&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt; &lt;strong&gt;High-Level Metric Monitoring&lt;/strong&gt;: Grafana metrics charts track the overall request throughput, purchase revenue, and HTTP error rate.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Drill-down to Latency&lt;/strong&gt;: Under the average latency chart, when a spike occurs, you notice the &lt;code&gt;/checkout&lt;/code&gt; route takes 2.2 seconds.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Distributed Tracing Correlation&lt;/strong&gt;: Because the trace context was propagated from &lt;code&gt;/checkout&lt;/code&gt; down to &lt;code&gt;/inventory/deduct&lt;/code&gt;, you can jump directly from Grafana into &lt;strong&gt;Jaeger&lt;/strong&gt; to examine the trace hierarchy.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Root-Cause Isolation&lt;/strong&gt;: In Jaeger, you see that the parent span &lt;code&gt;checkout_transaction&lt;/code&gt; spent 95% of its execution time inside the child span &lt;code&gt;inventory_deduct_span&lt;/code&gt;. Looking at the span details, you see &lt;code&gt;simulation.latency_added: 2.15&lt;/code&gt;, pointing directly to the simulated network lag!&lt;/li&gt;
&lt;/ol&gt;




&lt;h2&gt;
  
  
  7. Observability Best Practices for Production
&lt;/h2&gt;

&lt;p&gt;If you are implementing observability in production, keep these best practices in mind:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt; &lt;strong&gt;Use an OpenTelemetry Collector&lt;/strong&gt;: In local development, exporting telemetry directly from the app to Prometheus/Jaeger is fine. In production, however, your application should stream telemetry data asynchronously via OTLP to a local &lt;strong&gt;OTel Collector&lt;/strong&gt; daemon. The Collector processes, batches, and exports the data to your telemetry backend. This prevents application slowdowns during backend bottlenecks.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Inject Trace Context into Logs&lt;/strong&gt;: Configure your logger (e.g., Python &lt;code&gt;logging&lt;/code&gt; or &lt;code&gt;structlog&lt;/code&gt;) to format logs as JSON and inject the active trace ID (&lt;code&gt;trace.get_current_span().get_span_context().trace_id&lt;/code&gt;). This bridges the gap between logging and tracing.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Watch Out for Metric Cardinality&lt;/strong&gt;: When defining metrics, do not add attributes with high cardinality (e.g. user IDs, order IDs, or session IDs) as tags. Adding tags with infinite possible values will bloat your metric database memory and crash Prometheus. Use traces or logs for high-cardinality attributes.&lt;/li&gt;
&lt;li&gt; &lt;strong&gt;Enforce Sampling&lt;/strong&gt;: Sending 100% of traces to your collector is expensive and unnecessary for high-traffic applications. Configure adaptive or head-based sampling (e.g., sample 5% of successful checkouts, but 100% of errors).&lt;/li&gt;
&lt;/ol&gt;




&lt;h2&gt;
  
  
  Conclusion
&lt;/h2&gt;

&lt;p&gt;Observability is not just about installing software packages; it is an engineering discipline. Adopting OpenTelemetry ensures you decouple your application logic from any particular monitoring vendor. &lt;/p&gt;

&lt;p&gt;Setting up unified tracing and metric aggregation, as shown in our E-Commerce demo, allows your team to go from identifying a high-level error spike to isolating the exact line of failing code or latency bottleneck in seconds.&lt;/p&gt;

</description>
      <category>microservices</category>
      <category>monitoring</category>
      <category>python</category>
      <category>tutorial</category>
    </item>
    <item>
      <title>Enterprise Design Patterns: The Repository Pattern in Practice</title>
      <dc:creator>Hashira Belén Vargas Candia</dc:creator>
      <pubDate>Wed, 01 Jul 2026 06:05:31 +0000</pubDate>
      <link>https://dev.to/hashiravc/enterprise-design-patterns-the-repository-pattern-in-practice-2oci</link>
      <guid>https://dev.to/hashiravc/enterprise-design-patterns-the-repository-pattern-in-practice-2oci</guid>
      <description>&lt;p&gt;&lt;strong&gt;Curso:&lt;/strong&gt; Patrones de Software&lt;br&gt;
&lt;strong&gt;Basado en:&lt;/strong&gt; &lt;a href="https://martinfowler.com/eaaCatalog/" rel="noopener noreferrer"&gt;Catalog of Patterns of Enterprise Application Architecture, Martin Fowler&lt;/a&gt;&lt;/p&gt;




&lt;h2&gt;
  
  
  1. Introducción
&lt;/h2&gt;

&lt;p&gt;Martin Fowler, en su libro &lt;em&gt;Patterns of Enterprise Application Architecture&lt;/em&gt; (2002), documentó un conjunto de soluciones recurrentes a problemas que aparecen una y otra vez al construir software empresarial: cómo organizar la lógica de negocio, cómo mapear objetos a bases de datos, cómo estructurar la capa de presentación, entre otros. Su &lt;a href="https://martinfowler.com/eaaCatalog/" rel="noopener noreferrer"&gt;catálogo online&lt;/a&gt; agrupa estos patrones en categorías como &lt;em&gt;Domain Logic Patterns&lt;/em&gt;, &lt;em&gt;Data Source Architectural Patterns&lt;/em&gt;, &lt;em&gt;Object-Relational Behavioral Patterns&lt;/em&gt;, etc.&lt;/p&gt;

&lt;p&gt;En este artículo desarrollo el patrón &lt;strong&gt;Repository&lt;/strong&gt;, perteneciente a la categoría de &lt;em&gt;Object-Relational Behavioral Patterns&lt;/em&gt;, y lo acompaño con una implementación real en Python.&lt;/p&gt;

&lt;h2&gt;
  
  
  2. ¿Qué es el patrón Repository?
&lt;/h2&gt;

&lt;p&gt;Fowler define el Repository como una capa que &lt;strong&gt;media entre el dominio y la capa de acceso a datos&lt;/strong&gt;, comportándose como una colección de objetos en memoria. La idea central es que el resto de la aplicación (los casos de uso, los servicios, los controladores) no debería saber si los datos vienen de una base de datos SQL, de un archivo, de una API externa o de una lista en memoria. El Repository oculta esa complejidad detrás de una interfaz simple: &lt;code&gt;add()&lt;/code&gt;, &lt;code&gt;get()&lt;/code&gt;, &lt;code&gt;list()&lt;/code&gt;, &lt;code&gt;remove()&lt;/code&gt;.&lt;/p&gt;

&lt;h3&gt;
  
  
  Problema que resuelve
&lt;/h3&gt;

&lt;p&gt;Sin este patrón, es común ver consultas SQL o código de ORM esparcido por toda la lógica de negocio. Esto genera:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Acoplamiento fuerte entre la lógica de negocio y la tecnología de persistencia.&lt;/li&gt;
&lt;li&gt;Dificultad para probar el código (hay que levantar una base de datos real para cada test).&lt;/li&gt;
&lt;li&gt;Duplicación de queries similares en distintos puntos del sistema.&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Solución
&lt;/h3&gt;

&lt;p&gt;Se define una &lt;strong&gt;interfaz abstracta&lt;/strong&gt; (un contrato) que declara las operaciones disponibles sobre una colección de objetos de dominio, y luego se implementan una o varias &lt;strong&gt;versiones concretas&lt;/strong&gt; de esa interfaz (por ejemplo, una para SQLite, otra en memoria para pruebas, otra para MongoDB, etc.). El resto del sistema solo depende de la interfaz, nunca de la implementación concreta.&lt;/p&gt;

&lt;h2&gt;
  
  
  3. Ejemplo real de código (Python)
&lt;/h2&gt;

&lt;p&gt;El ejemplo modela un sistema simple de &lt;strong&gt;gestión de pedidos (Orders)&lt;/strong&gt; para una tienda. Se define:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt;Una entidad de dominio &lt;code&gt;Order&lt;/code&gt;.&lt;/li&gt;
&lt;li&gt;Una interfaz abstracta &lt;code&gt;OrderRepository&lt;/code&gt;.&lt;/li&gt;
&lt;li&gt;Dos implementaciones: &lt;code&gt;InMemoryOrderRepository&lt;/code&gt; (para pruebas unitarias) y &lt;code&gt;SqliteOrderRepository&lt;/code&gt; (para producción).&lt;/li&gt;
&lt;li&gt;Un caso de uso (&lt;code&gt;OrderService&lt;/code&gt;) que depende únicamente de la interfaz.&lt;/li&gt;
&lt;/ol&gt;

&lt;h3&gt;
  
  
  3.1 Entidad de dominio
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="c1"&gt;# src/domain.py
&lt;/span&gt;&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;dataclasses&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;dataclass&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;field&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;datetime&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;datetime&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;uuid&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;uuid4&lt;/span&gt;


&lt;span class="nd"&gt;@dataclass&lt;/span&gt;
&lt;span class="k"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="n"&gt;customer_name&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;
    &lt;span class="n"&gt;total_amount&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;float&lt;/span&gt;
    &lt;span class="nb"&gt;id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;field&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;default_factory&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="k"&gt;lambda&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nf"&gt;str&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nf"&gt;uuid4&lt;/span&gt;&lt;span class="p"&gt;()))&lt;/span&gt;
    &lt;span class="n"&gt;created_at&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;datetime&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;field&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;default_factory&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;datetime&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;utcnow&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;apply_discount&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;percentage&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;float&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="ow"&gt;not&lt;/span&gt; &lt;span class="mi"&gt;0&lt;/span&gt; &lt;span class="o"&gt;&amp;lt;=&lt;/span&gt; &lt;span class="n"&gt;percentage&lt;/span&gt; &lt;span class="o"&gt;&amp;lt;=&lt;/span&gt; &lt;span class="mi"&gt;100&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
            &lt;span class="k"&gt;raise&lt;/span&gt; &lt;span class="nc"&gt;ValueError&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;El descuento debe estar entre 0 y 100&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;total_amount&lt;/span&gt; &lt;span class="o"&gt;-=&lt;/span&gt; &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;total_amount&lt;/span&gt; &lt;span class="o"&gt;*&lt;/span&gt; &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;percentage&lt;/span&gt; &lt;span class="o"&gt;/&lt;/span&gt; &lt;span class="mi"&gt;100&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  3.2 Interfaz del Repository (el contrato)
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="c1"&gt;# src/repository.py
&lt;/span&gt;&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;abc&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;ABC&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;abstractmethod&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;typing&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;List&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;Optional&lt;/span&gt;

&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;.domain&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;


&lt;span class="k"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;OrderRepository&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;ABC&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
    &lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;Contrato que toda implementación de persistencia debe cumplir.
    La lógica de negocio solo conoce esta interfaz, nunca los detalles
    de SQLite, memoria, MongoDB, etc.
    &lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;

    &lt;span class="nd"&gt;@abstractmethod&lt;/span&gt;
    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="bp"&gt;...&lt;/span&gt;

    &lt;span class="nd"&gt;@abstractmethod&lt;/span&gt;
    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="n"&gt;Optional&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;]:&lt;/span&gt; &lt;span class="bp"&gt;...&lt;/span&gt;

    &lt;span class="nd"&gt;@abstractmethod&lt;/span&gt;
    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;list_all&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="n"&gt;List&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;]:&lt;/span&gt; &lt;span class="bp"&gt;...&lt;/span&gt;

    &lt;span class="nd"&gt;@abstractmethod&lt;/span&gt;
    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;remove&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="bp"&gt;...&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  3.3 Implementación en memoria (ideal para tests)
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="c1"&gt;# src/in_memory_repository.py
&lt;/span&gt;&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;typing&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;Dict&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;List&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;Optional&lt;/span&gt;

&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;.domain&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;.repository&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;OrderRepository&lt;/span&gt;


&lt;span class="k"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;InMemoryOrderRepository&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;OrderRepository&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;__init__&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_orders&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;Dict&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{}&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_orders&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nb"&gt;id&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;order&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="n"&gt;Optional&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;]:&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_orders&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;list_all&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="n"&gt;List&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;]:&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nf"&gt;list&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_orders&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;values&lt;/span&gt;&lt;span class="p"&gt;())&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;remove&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_orders&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;pop&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  3.4 Implementación con SQLite (persistencia real)
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="c1"&gt;# src/sqlite_repository.py
&lt;/span&gt;&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;sqlite3&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;datetime&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;datetime&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;typing&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;List&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;Optional&lt;/span&gt;

&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;.domain&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;.repository&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;OrderRepository&lt;/span&gt;


&lt;span class="k"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;SqliteOrderRepository&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;OrderRepository&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;__init__&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;db_path&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;orders.db&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_conn&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;sqlite3&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;connect&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;db_path&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;_create_table&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;_create_table&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;execute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
            &lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;
            CREATE TABLE IF NOT EXISTS orders (
                id TEXT PRIMARY KEY,
                customer_name TEXT NOT NULL,
                total_amount REAL NOT NULL,
                created_at TEXT NOT NULL
            )
            &lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;
        &lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;commit&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;execute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
            &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;INSERT OR REPLACE INTO orders VALUES (?, ?, ?, ?)&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nb"&gt;id&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;customer_name&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;total_amount&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
             &lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;created_at&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;isoformat&lt;/span&gt;&lt;span class="p"&gt;()),&lt;/span&gt;
        &lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;commit&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="n"&gt;Optional&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;]:&lt;/span&gt;
        &lt;span class="n"&gt;row&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;execute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
            &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;SELECT id, customer_name, total_amount, created_at FROM orders WHERE id = ?&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;,),&lt;/span&gt;
        &lt;span class="p"&gt;).&lt;/span&gt;&lt;span class="nf"&gt;fetchone&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;_row_to_order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;row&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;row&lt;/span&gt; &lt;span class="k"&gt;else&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;list_all&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="n"&gt;List&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;]:&lt;/span&gt;
        &lt;span class="n"&gt;rows&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;execute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
            &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;SELECT id, customer_name, total_amount, created_at FROM orders&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;
        &lt;span class="p"&gt;).&lt;/span&gt;&lt;span class="nf"&gt;fetchall&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;_row_to_order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;row&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;for&lt;/span&gt; &lt;span class="n"&gt;row&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="n"&gt;rows&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;remove&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;execute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;DELETE FROM orders WHERE id = ?&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;,))&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_conn&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;commit&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;

    &lt;span class="nd"&gt;@staticmethod&lt;/span&gt;
    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;_row_to_order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;row&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nc"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
            &lt;span class="nb"&gt;id&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;row&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="mi"&gt;0&lt;/span&gt;&lt;span class="p"&gt;],&lt;/span&gt;
            &lt;span class="n"&gt;customer_name&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;row&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;],&lt;/span&gt;
            &lt;span class="n"&gt;total_amount&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;row&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="mi"&gt;2&lt;/span&gt;&lt;span class="p"&gt;],&lt;/span&gt;
            &lt;span class="n"&gt;created_at&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;datetime&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;fromisoformat&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;row&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="mi"&gt;3&lt;/span&gt;&lt;span class="p"&gt;]),&lt;/span&gt;
        &lt;span class="p"&gt;)&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  3.5 Caso de uso desacoplado de la persistencia
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="c1"&gt;# src/service.py
&lt;/span&gt;&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;.domain&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;.repository&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;OrderRepository&lt;/span&gt;


&lt;span class="k"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;OrderService&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="sh"&gt;"""&lt;/span&gt;&lt;span class="s"&gt;Depende solo de la abstracción OrderRepository.
    No sabe -ni le importa- si los pedidos viven en SQLite o en memoria.
    &lt;/span&gt;&lt;span class="sh"&gt;"""&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;__init__&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;repository&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;OrderRepository&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_repository&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;repository&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;place_order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;customer_name&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;total_amount&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;float&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;order&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;customer_name&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;customer_name&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;total_amount&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="n"&gt;total_amount&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_repository&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="n"&gt;order&lt;/span&gt;

    &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;apply_discount_to_order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;str&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;percentage&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;float&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="n"&gt;Order&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="n"&gt;order&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_repository&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;order&lt;/span&gt; &lt;span class="ow"&gt;is&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
            &lt;span class="k"&gt;raise&lt;/span&gt; &lt;span class="nc"&gt;ValueError&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Pedido &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;order_id&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s"&gt; no encontrado&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;apply_discount&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;percentage&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
        &lt;span class="n"&gt;self&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_repository&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;  &lt;span class="c1"&gt;# actualiza
&lt;/span&gt;        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="n"&gt;order&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  3.6 Demostración: intercambiando implementaciones sin tocar la lógica
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="c1"&gt;# main.py
&lt;/span&gt;&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;src.in_memory_repository&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;InMemoryOrderRepository&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;src.sqlite_repository&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;SqliteOrderRepository&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;src.service&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;OrderService&lt;/span&gt;


&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;run_demo&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;repository&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
    &lt;span class="n"&gt;service&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;OrderService&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;repository&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;order&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;service&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;place_order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Ariana Quispe&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;250.00&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="nf"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Pedido creado: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="n"&gt;updated&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;service&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;apply_discount_to_order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nb"&gt;id&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mi"&gt;10&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="nf"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Pedido con descuento: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;updated&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="nf"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Todos los pedidos:&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;service&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_repository&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;list_all&lt;/span&gt;&lt;span class="p"&gt;())&lt;/span&gt;


&lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;__name__&lt;/span&gt; &lt;span class="o"&gt;==&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;__main__&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="nf"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;--- Usando repositorio en memoria ---&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="nf"&gt;run_demo&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nc"&gt;InMemoryOrderRepository&lt;/span&gt;&lt;span class="p"&gt;())&lt;/span&gt;

    &lt;span class="nf"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="se"&gt;\n&lt;/span&gt;&lt;span class="s"&gt;--- Usando repositorio SQLite (persistente) ---&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="nf"&gt;run_demo&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nc"&gt;SqliteOrderRepository&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;orders.db&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;))&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;&lt;strong&gt;Punto clave del ejemplo:&lt;/strong&gt; &lt;code&gt;OrderService&lt;/code&gt; nunca cambia. Basta con inyectarle un repositorio distinto (&lt;code&gt;InMemoryOrderRepository&lt;/code&gt; o &lt;code&gt;SqliteOrderRepository&lt;/code&gt;) para cambiar completamente la forma en que se persisten los datos. Esto es exactamente el beneficio que describe Fowler: la lógica de dominio queda aislada de los detalles de infraestructura.&lt;/p&gt;

&lt;h2&gt;
  
  
  4. Pruebas unitarias (ventaja directa del patrón)
&lt;/h2&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight python"&gt;&lt;code&gt;&lt;span class="c1"&gt;# tests/test_order_service.py
&lt;/span&gt;&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;pytest&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;src.in_memory_repository&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;InMemoryOrderRepository&lt;/span&gt;
&lt;span class="kn"&gt;from&lt;/span&gt; &lt;span class="n"&gt;src.service&lt;/span&gt; &lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="n"&gt;OrderService&lt;/span&gt;


&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;test_place_order_stores_it_in_repository&lt;/span&gt;&lt;span class="p"&gt;():&lt;/span&gt;
    &lt;span class="n"&gt;repo&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;InMemoryOrderRepository&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
    &lt;span class="n"&gt;service&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;OrderService&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;repo&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="n"&gt;order&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;service&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;place_order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Gustavo Mamani&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;100.0&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;


    &lt;span class="k"&gt;assert&lt;/span&gt; &lt;span class="n"&gt;repo&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nb"&gt;id&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="ow"&gt;is&lt;/span&gt; &lt;span class="ow"&gt;not&lt;/span&gt; &lt;span class="bp"&gt;None&lt;/span&gt;
    &lt;span class="k"&gt;assert&lt;/span&gt; &lt;span class="n"&gt;repo&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nb"&gt;id&lt;/span&gt;&lt;span class="p"&gt;).&lt;/span&gt;&lt;span class="n"&gt;customer_name&lt;/span&gt; &lt;span class="o"&gt;==&lt;/span&gt; &lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Gustavo Mamani&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;


&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;test_apply_discount_updates_total_amount&lt;/span&gt;&lt;span class="p"&gt;():&lt;/span&gt;
    &lt;span class="n"&gt;repo&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;InMemoryOrderRepository&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
    &lt;span class="n"&gt;service&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nc"&gt;OrderService&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;repo&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="n"&gt;order&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;service&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;place_order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="s"&gt;Hashira&lt;/span&gt;&lt;span class="sh"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;200.0&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="n"&gt;updated&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;service&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;apply_discount_to_order&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;order&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nb"&gt;id&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mi"&gt;25&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;

    &lt;span class="k"&gt;assert&lt;/span&gt; &lt;span class="n"&gt;updated&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;total_amount&lt;/span&gt; &lt;span class="o"&gt;==&lt;/span&gt; &lt;span class="mf"&gt;150.0&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Gracias a la interfaz &lt;code&gt;OrderRepository&lt;/code&gt;, estas pruebas corren en milisegundos, sin necesidad de una base de datos real — otro beneficio directo que Fowler atribuye al patrón.&lt;/p&gt;

&lt;h2&gt;
  
  
  5. Relación con otros patrones del catálogo
&lt;/h2&gt;

&lt;ul&gt;
&lt;li&gt;
&lt;strong&gt;Data Mapper&lt;/strong&gt;: el Repository suele apoyarse en un Data Mapper para traducir entre el objeto de dominio y las filas de la base de datos.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Unit of Work&lt;/strong&gt;: en sistemas más grandes, el Repository trabaja junto a un Unit of Work que agrupa varias operaciones en una sola transacción.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Service Layer&lt;/strong&gt;: &lt;code&gt;OrderService&lt;/code&gt; en este ejemplo cumple el rol de Service Layer, orquestando el dominio y delegando la persistencia al Repository.&lt;/li&gt;
&lt;/ul&gt;

&lt;h2&gt;
  
  
  6. Conclusión
&lt;/h2&gt;

&lt;p&gt;El patrón Repository es una de las herramientas más usadas hoy en arquitecturas limpias (&lt;em&gt;Clean Architecture&lt;/em&gt;, &lt;em&gt;Hexagonal Architecture&lt;/em&gt;) precisamente porque resuelve un problema muy concreto: desacoplar el "qué" (lógica de negocio) del "cómo" (tecnología de persistencia). El ejemplo en Python demuestra que, con una interfaz bien definida, es trivial cambiar de una implementación en memoria a una persistente sin tocar una sola línea de la lógica de negocio.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Repository&lt;/strong&gt; &lt;a href="https://github.com/Hashiravc/repository-pattern.git" rel="noopener noreferrer"&gt;https://github.com/Hashiravc/repository-pattern.git&lt;/a&gt;&lt;/p&gt;

&lt;h2&gt;
  
  
  Referencias
&lt;/h2&gt;

&lt;ul&gt;
&lt;li&gt;Fowler, M. (2002). &lt;em&gt;Patterns of Enterprise Application Architecture&lt;/em&gt;. Addison-Wesley.&lt;/li&gt;
&lt;li&gt;Fowler, M. &lt;em&gt;Repository&lt;/em&gt;. Catalog of Patterns of Enterprise Application Architecture. &lt;a href="https://martinfowler.com/eaaCatalog/repository.html" rel="noopener noreferrer"&gt;https://martinfowler.com/eaaCatalog/repository.html&lt;/a&gt;
&lt;/li&gt;
&lt;li&gt;Catálogo completo: &lt;a href="https://martinfowler.com/eaaCatalog/" rel="noopener noreferrer"&gt;https://martinfowler.com/eaaCatalog/&lt;/a&gt;
&lt;/li&gt;
&lt;/ul&gt;

</description>
    </item>
    <item>
      <title>Applying Fortify Static Code Analyzer to a Node.js Application: A Practical Guide</title>
      <dc:creator>Hashira Belén Vargas Candia</dc:creator>
      <pubDate>Sat, 06 Dec 2025 04:34:32 +0000</pubDate>
      <link>https://dev.to/hashiravc/applying-fortify-static-code-analyzer-to-a-nodejs-application-a-practical-guide-2fen</link>
      <guid>https://dev.to/hashiravc/applying-fortify-static-code-analyzer-to-a-nodejs-application-a-practical-guide-2fen</guid>
      <description>&lt;p&gt;Article by: Hashira Belén Vargas Candia&lt;br&gt;
Systems Engineering Student – Application Security Focus&lt;/p&gt;
&lt;h2&gt;
  
  
  Introduction to SAST Tools
&lt;/h2&gt;

&lt;p&gt;Static Application Security Testing (SAST) tools analyze source code to identify security vulnerabilities before the application is deployed. While tools like SonarQube, Snyk, and Semgrep are popular, this article explores Micro Focus Fortify Static Code Analyzer (SCA) – an enterprise-grade SAST solution for comprehensive security analysis.&lt;/p&gt;
&lt;h2&gt;
  
  
  Why Fortify SCA?
&lt;/h2&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;Fortify SCA offers:&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Multi-language support (Java, .NET, C++, Python, JavaScript, etc.)&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Deep code analysis with data flow and control flow tracking&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Comprehensive vulnerability database (OWASP Top 10, CWE, etc.)&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Integration capabilities with CI/CD pipelines&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Detailed remediation guidance&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;
&lt;h2&gt;
  
  
  Setting Up Fortify SCA for a Node.js Application
&lt;/h2&gt;
&lt;h3&gt;
  
  
  Prerequisites
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;Micro Focus Fortify SCA installation&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Node.js project with source code&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Fortify Plugin for your IDE (optional)&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;
&lt;h2&gt;
  
  
  Step 1: Installation &amp;amp; Setup
&lt;/h2&gt;


&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;# Download Fortify SCA from official Micro Focus portal
# Install with default settings
# Verify installation
fortify version
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;

&lt;h2&gt;
  
  
  Step 2: Configure Scan Settings
&lt;/h2&gt;

&lt;p&gt;Create a fortify-sca.properties file:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;# Scan configuration for Node.js application
com.fortify.sca.Phase0HigherOrder.Languages=javascript
com.fortify.sca.EnableHTML5Scan=true
com.fortify.sca.NPM.EnableDependencyScanning=true
com.fortify.sca.Yarn.EnableDependencyScanning=true
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  Step 3: Running the Scan
&lt;/h2&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;# Navigate to your Node.js project directory
cd /path/to/your/nodejs-app

# Run sourceanalyzer to translate source code
sourceanalyzer -b myNodeAppBuild -clean
sourceanalyzer -b myNodeAppBuild -source 1.8 **/*.js **/*.ts **/*.jsx **/*.tsx

# Scan for vulnerabilities
fortifyclient start scan -b myNodeAppBuild
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  Real-World Example: Vulnerable Node.js Code
&lt;/h2&gt;

&lt;h3&gt;
  
  
  Before SAST Analysis
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;// app.js - Vulnerable code examples

// 1. SQL Injection vulnerability
app.get('/users', (req, res) =&amp;gt; {
    const userId = req.query.id;
    // UNSAFE: Direct string concatenation
    db.query(`SELECT * FROM users WHERE id = ${userId}`, (err, result) =&amp;gt; {
        res.json(result);
    });
});

// 2. XSS vulnerability
app.post('/comment', (req, res) =&amp;gt; {
    const comment = req.body.comment;
    // UNSAFE: Direct DOM injection
    res.send(`&amp;lt;div&amp;gt;${comment}&amp;lt;/div&amp;gt;`);
});

// 3. Hardcoded credentials
const dbPassword = 'Admin@123'; // Security issue
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  After Fortify SCA Analysis &amp;amp; Fixes
&lt;/h2&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;// app.js - Secure code after remediation

// 1. Fixed SQL Injection using parameterized queries
app.get('/users', (req, res) =&amp;gt; {
    const userId = req.query.id;
    // SAFE: Parameterized query
    db.query('SELECT * FROM users WHERE id = ?', [userId], (err, result) =&amp;gt; {
        res.json(result);
    });
});

// 2. Fixed XSS using output encoding
const escapeHtml = require('escape-html');
app.post('/comment', (req, res) =&amp;gt; {
    const comment = req.body.comment;
    // SAFE: HTML escaping
    res.send(`&amp;lt;div&amp;gt;${escapeHtml(comment)}&amp;lt;/div&amp;gt;`);
});

// 3. Removed hardcoded credentials
const dbPassword = process.env.DB_PASSWORD; // From environment variables
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  Understanding Fortify Scan Results
&lt;/h2&gt;

&lt;h3&gt;
  
  
  Sample Output Format
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;{
  "issues": [
    {
      "id": "CWE-89",
      "severity": "High",
      "category": "SQL Injection",
      "file": "/src/routes/users.js",
      "line": 45,
      "description": "User input flows into SQL query without validation",
      "recommendation": "Use parameterized queries or stored procedures"
    },
    {
      "id": "CWE-79",
      "severity": "Medium",
      "category": "Cross-Site Scripting (XSS)",
      "file": "/src/views/comments.ejs",
      "line": 23,
      "description": "User input directly reflected in HTML output",
      "recommendation": "Implement proper output encoding"
    }
  ],
  "summary": {
    "total_issues": 15,
    "high_severity": 3,
    "medium_severity": 8,
    "low_severity": 4
  }
}
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  Severity Classification
&lt;/h2&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;Critical/High: Immediate attention required (SQLi, RCE, etc.)&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Medium: Address in next development cycle (XSS, CSRF, etc.)&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Low: Consider fixing (information disclosure, etc.)&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;h2&gt;
  
  
  Integrating Fortify SCA into CI/CD Pipeline
&lt;/h2&gt;

&lt;h3&gt;
  
  
  GitHub Actions Integration
&lt;/h3&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;# .github/workflows/fortify-scan.yml
name: Fortify SAST Scan

on: [push, pull_request]

jobs:
  fortify-scan:
    runs-on: ubuntu-latest

    steps:
    - name: Checkout code
      uses: actions/checkout@v3

    - name: Set up Node.js
      uses: actions/setup-node@v3
      with:
        node-version: '18'

    - name: Install dependencies
      run: npm ci

    - name: Download Fortify SCA
      run: |
        wget https://download.fortify.com/sca/fortify-sca-latest.zip
        unzip fortify-sca-latest.zip

    - name: Run Fortify Scan
      run: |
        ./fortify-sca/bin/sourceanalyzer -b ${{ github.run_id }} -clean
        ./fortify-sca/bin/sourceanalyzer -b ${{ github.run_id }} **/*.js
        ./fortify-sca/bin/fortifyclient start scan -b ${{ github.run_id }}

    - name: Upload Results
      uses: actions/upload-artifact@v3
      with:
        name: fortify-results
        path: fortify-reports/
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  GitLab CI/CD Integration
&lt;/h2&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;# .gitlab-ci.yml
stages:
  - test
  - security

fortify_sast:
  stage: security
  image: node:18
  before_script:
    - apt-get update &amp;amp;&amp;amp; apt-get install -y wget unzip
    - wget https://download.fortify.com/sca/fortify-sca-latest.zip
    - unzip fortify-sca-latest.zip
  script:
    - npm ci
    - ./fortify-sca/bin/sourceanalyzer -b $CI_PIPELINE_ID -clean
    - ./fortify-sca/bin/sourceanalyzer -b $CI_PIPELINE_ID **/*.js
    - ./fortify-sca/bin/fortifyclient start scan -b $CI_PIPELINE_ID
  artifacts:
    paths:
      - fortify-reports/
    when: always
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  Best Practices for SAST Implementation
&lt;/h2&gt;

&lt;ol&gt;
&lt;li&gt;Regular Scanning Schedule&lt;/li&gt;
&lt;li&gt;Pre-commit hooks: Scan before each commit&lt;/li&gt;
&lt;/ol&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;Nightly builds: Comprehensive scans during off-hours&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Release gates: Mandatory scans before production deployment&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;ol&gt;
&lt;li&gt;Tuning &amp;amp; Customization
&lt;/li&gt;
&lt;/ol&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;# Custom rule pack configuration
com.fortify.sca.CustomRules.Path=/path/to/custom/rules.xml
com.fortify.sca.SuppressionFilter.Path=/path/to/false-positives.xml
com.fortify.sca.Severity.Threshold=Medium
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;ol&gt;
&lt;li&gt;Developer Education&lt;/li&gt;
&lt;li&gt;Remediation workshops: How to fix identified issues&lt;/li&gt;
&lt;li&gt;Secure coding training: Preventing vulnerabilities at source&lt;/li&gt;
&lt;li&gt;Knowledge sharing: Internal security champions program&lt;/li&gt;
&lt;/ol&gt;

&lt;h3&gt;
  
  
  Comparison with Other SAST Tools
&lt;/h3&gt;

&lt;div class="table-wrapper-paragraph"&gt;&lt;table&gt;
&lt;thead&gt;
&lt;tr&gt;
&lt;th&gt;Feature&lt;/th&gt;
&lt;th&gt;Fortify SCA&lt;/th&gt;
&lt;th&gt;Checkmarx&lt;/th&gt;
&lt;th&gt;CodeQL&lt;/th&gt;
&lt;/tr&gt;
&lt;/thead&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Language Support&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;25+ languages&lt;/td&gt;
&lt;td&gt;25+ languages&lt;/td&gt;
&lt;td&gt;10+ languages&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Analysis Depth&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Deep flow analysis&lt;/td&gt;
&lt;td&gt;Flow analysis&lt;/td&gt;
&lt;td&gt;Semantic analysis&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Integration&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Extensive CI/CD plugins&lt;/td&gt;
&lt;td&gt;Good integration&lt;/td&gt;
&lt;td&gt;GitHub native&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Learning Curve&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Moderate to steep&lt;/td&gt;
&lt;td&gt;Moderate&lt;/td&gt;
&lt;td&gt;Moderate&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Reporting&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Enterprise-grade&lt;/td&gt;
&lt;td&gt;Comprehensive&lt;/td&gt;
&lt;td&gt;GitHub-focused&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;/div&gt;

&lt;h3&gt;
  
  
  Common Challenges &amp;amp; Solutions
&lt;/h3&gt;

&lt;div class="table-wrapper-paragraph"&gt;&lt;table&gt;
&lt;thead&gt;
&lt;tr&gt;
&lt;th&gt;Challenge&lt;/th&gt;
&lt;th&gt;Solution&lt;/th&gt;
&lt;/tr&gt;
&lt;/thead&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;False Positives&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Create suppression filters for known false positives&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Long Scan Times&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Implement incremental scanning&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Complex Setup&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Use containerized deployment&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;High Resource Usage&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Optimize scan configurations and schedule off-hours&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Developer Resistance&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Provide training and integrate smoothly into workflow&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;/div&gt;

&lt;h4&gt;
  
  
  Challenge 1: False Positives
&lt;/h4&gt;

&lt;p&gt;Solution: Create suppression filters for known false positives&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;&amp;lt;!-- false-positives.xml --&amp;gt;
&amp;lt;SuppressionFilters&amp;gt;
  &amp;lt;Suppress&amp;gt;
    &amp;lt;RuleID&amp;gt;CWE-78&amp;lt;/RuleID&amp;gt;
    &amp;lt;File&amp;gt;.*legacy-code\.js&amp;lt;/File&amp;gt;
  &amp;lt;/Suppress&amp;gt;
&amp;lt;/SuppressionFilters&amp;gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h4&gt;
  
  
  Challenge 2: Long Scan Times
&lt;/h4&gt;

&lt;p&gt;Solution: Implement incremental scanning&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;## Only scan changed files
sourceanalyzer -b myApp -incremental
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h4&gt;
  
  
  Challenge 3: Complex Setup
&lt;/h4&gt;

&lt;p&gt;Solution: Use containerized deployment&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;# Dockerfile for Fortify SCA
FROM node:18
RUN wget https://download.fortify.com/sca/fortify-sca-latest.zip
RUN unzip fortify-sca-latest.zip
COPY . /app
WORKDIR /app
CMD ["./run-fortify-scan.sh"]
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  Conclusion
&lt;/h2&gt;

&lt;p&gt;Fortify Static Code Analyzer provides robust security scanning for applications across multiple programming languages. While it requires initial setup and configuration, its comprehensive vulnerability detection and detailed remediation guidance make it valuable for enterprise security programs.&lt;/p&gt;

&lt;h4&gt;
  
  
  Key takeaways:
&lt;/h4&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;SAST tools like Fortify catch vulnerabilities early in development&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Integration with CI/CD pipelines enables automated security testing&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Regular scans and developer education significantly improve application security&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Proper tuning reduces false positives and increases tool effectiveness&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;h2&gt;
  
  
  Additional Resources
&lt;/h2&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;OWASP SAST Tools List&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Fortify SCA Documentation&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;NIST Application Security Guidelines&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Secure Coding Practices Checklist&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

</description>
    </item>
    <item>
      <title>A Real-World Comparison of Testing Management Tools: GitHub Actions vs GitLab CI/CDs</title>
      <dc:creator>Hashira Belén Vargas Candia</dc:creator>
      <pubDate>Thu, 04 Dec 2025 05:20:49 +0000</pubDate>
      <link>https://dev.to/hashiravc/a-real-world-comparison-of-testing-management-tools-github-actions-vs-gitlab-cicds-52g</link>
      <guid>https://dev.to/hashiravc/a-real-world-comparison-of-testing-management-tools-github-actions-vs-gitlab-cicds-52g</guid>
      <description>&lt;p&gt;Article by: Hashira Belén Vargas Candia&lt;br&gt;
Systems Engineering Student – CI/CD &amp;amp; DevOps Focus&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Introduction&lt;/strong&gt;&lt;br&gt;
In modern software development, continuous integration and delivery (CI/CD) are essential for ensuring code quality and fast deployments. Automated testing tools allow test suites to run automatically with every code change. In this article, I will compare two of the most popular tools: GitHub Actions and GitLab CI/CD, providing real configuration examples.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;GitHub Actions&lt;/strong&gt;&lt;br&gt;
Overview&lt;br&gt;
GitHub Actions is the native CI/CD solution integrated directly into GitHub. It allows workflow automation using YAML files in the .github/workflows directory. It is highly flexible, with a marketplace of pre-built actions and support for Docker containers.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Example Configuration&lt;/strong&gt;&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;# .github/workflows/run-tests.yml
name: Run Tests

on:
  push:
    branches: [ main, develop ]
  pull_request:
    branches: [ main ]

jobs:
  test:
    runs-on: ubuntu-latest

    steps:
    - name: Checkout code
      uses: actions/checkout@v3

    - name: Set up Node.js
      uses: actions/setup-node@v3
      with:
        node-version: '18'

    - name: Install dependencies
      run: npm ci

    - name: Run unit tests
      run: npm test

    - name: Run integration tests
      run: npm run test:integration

    - name: Upload coverage reports
      uses: codecov/codecov-action@v3
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;&lt;strong&gt;GitLab CI/CD&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;Overview&lt;br&gt;
GitLab CI/CD is the continuous integration tool included within the GitLab platform. It is configured using a .gitlab-ci.yml file in the repository root. It offers visual pipelines, deployment environments, and deep integration with the DevOps lifecycle.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Example Configuration&lt;/strong&gt;&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;# .gitlab-ci.yml
stages:
  - test
  - deploy

unit_tests:
  stage: test
  image: node:18-alpine
  script:
    - npm ci
    - npm test
  artifacts:
    when: always
    paths:
      - coverage/
    reports:
      junit: junit.xml

integration_tests:
  stage: test
  image: node:18-alpine
  services:
    - postgres:latest
  variables:
    POSTGRES_DB: test_db
    POSTGRES_USER: runner
    POSTGRES_PASSWORD: ""
  script:
    - npm ci
    - npm run test:integration

pages:
  stage: deploy
  script:
    - npm run build:coverage
  artifacts:
    paths:
      - public
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;&lt;strong&gt;Detailed Comparison&lt;/strong&gt;&lt;/p&gt;

&lt;div class="table-wrapper-paragraph"&gt;&lt;table&gt;
&lt;thead&gt;
&lt;tr&gt;
&lt;th&gt;Feature&lt;/th&gt;
&lt;th&gt;GitHub Actions&lt;/th&gt;
&lt;th&gt;GitLab CI/CD&lt;/th&gt;
&lt;/tr&gt;
&lt;/thead&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Native Integration&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;With GitHub (perfect if you use GitHub)&lt;/td&gt;
&lt;td&gt;With GitLab (complete DevOps ecosystem)&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Configuration Syntax&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;YAML with reusable actions&lt;/td&gt;
&lt;td&gt;YAML with defined stages and jobs&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Marketplace/Pre-built Actions&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Extensive GitHub Marketplace&lt;/td&gt;
&lt;td&gt;Reusable templates and components&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Visual Environments&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Basic but functional&lt;/td&gt;
&lt;td&gt;More detailed visual pipelines&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Pricing for Private Repos&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;2000 free minutes/month&lt;/td&gt;
&lt;td&gt;400 free minutes/month on SaaS free tier&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Self-hosted Runners&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Yes (runners)&lt;/td&gt;
&lt;td&gt;Yes (GitLab runners)&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Cache and Artifacts&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Built-in support&lt;/td&gt;
&lt;td&gt;Very robust with configurable storage&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Kubernetes Integration&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Yes (via actions)&lt;/td&gt;
&lt;td&gt;Native and very strong&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;/div&gt;

&lt;p&gt;&lt;strong&gt;Real-World Use Case: Testing Pipeline for a REST API&lt;/strong&gt;&lt;br&gt;
Context&lt;br&gt;
I developed a REST API with Node.js/Express that requires:&lt;/p&gt;

&lt;p&gt;Unit tests (Jest)&lt;/p&gt;

&lt;p&gt;Integration tests with PostgreSQL&lt;/p&gt;

&lt;p&gt;Load testing (optional)&lt;/p&gt;

&lt;p&gt;Coverage reports&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;GitHub Actions Solution&lt;/strong&gt;&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;- name: Run load tests
  if: github.ref == 'refs/heads/main'
  run: |
    npm install -g artillery
    artillery run load-test.yml
GitLab CI/CD Solution
yaml
performance_tests:
  stage: test
  only:
    - main
  script:
    - npm install -g artillery
    - artillery run load-test.yml
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Both tools allow running load tests only on the main branch, optimizing resource usage.&lt;/p&gt;

&lt;h2&gt;
  
  
  Tool Selection Recommendations
&lt;/h2&gt;

&lt;p&gt;&lt;strong&gt;Choose GitHub Actions if:&lt;/strong&gt;&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;Your repository is already on GitHub&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;You need integration with many third-party tools*&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;You prefer a community-driven actions ecosystem&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Your team is small to medium and values simplicity&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;&lt;strong&gt;Choose GitLab CI/CD if:&lt;/strong&gt;&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;You already use GitLab for repository management&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;You need a complete DevOps pipeline (from issues to deploy)&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;You require native integration with Kubernetes&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;You work in a large team with auditing and security needs&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;&lt;strong&gt;Conclusion&lt;/strong&gt;&lt;br&gt;
Both GitHub Actions and GitLab CI/CD are powerful tools for test automation. The choice mainly depends on where your code is hosted and your specific DevOps workflow needs.&lt;/p&gt;

&lt;p&gt;GitHub Actions stands out for its simplicity and vast action ecosystem, while GitLab CI/CD offers deeper integration with the full development lifecycle. Both enable robust, scalable, and maintainable testing pipelines.&lt;/p&gt;

</description>
      <category>devops</category>
      <category>ci</category>
      <category>continuousdelivery</category>
      <category>automation</category>
    </item>
    <item>
      <title>Applying API Testing Frameworks: Real-World Examples with Swagger and JUnit</title>
      <dc:creator>Hashira Belén Vargas Candia</dc:creator>
      <pubDate>Tue, 04 Nov 2025 07:11:07 +0000</pubDate>
      <link>https://dev.to/hashiravc/the-future-of-machine-learning-in-api-testing-a-new-era-of-automation-260h</link>
      <guid>https://dev.to/hashiravc/the-future-of-machine-learning-in-api-testing-a-new-era-of-automation-260h</guid>
      <description>&lt;h2&gt;
  
  
  Introduction
&lt;/h2&gt;

&lt;p&gt;In today's software development landscape, APIs (Application Programming Interfaces) are essential for enabling communication between different systems. Ensuring that these APIs function correctly is crucial, which is why &lt;strong&gt;API testing&lt;/strong&gt; is an integral part of the development process.&lt;/p&gt;

&lt;p&gt;This article explores how to apply &lt;strong&gt;API testing frameworks&lt;/strong&gt; in real-world scenarios, using &lt;strong&gt;Swagger&lt;/strong&gt; and &lt;strong&gt;JUnit&lt;/strong&gt; as examples. These frameworks help automate and streamline the testing process, ensuring that APIs are functional, secure, and performant.&lt;/p&gt;

&lt;h2&gt;
  
  
  What is an API Testing Framework?
&lt;/h2&gt;

&lt;p&gt;An &lt;strong&gt;API testing framework&lt;/strong&gt; is a set of tools, libraries, and processes that facilitate the testing of APIs. The goal of such a framework is to standardize the testing process, making it easier to write, run, and maintain tests for APIs across different endpoints and services.&lt;/p&gt;

&lt;h3&gt;
  
  
  Benefits of Using an API Testing Framework:
&lt;/h3&gt;

&lt;ul&gt;
&lt;li&gt;
&lt;strong&gt;Automation&lt;/strong&gt;: Reduces manual effort by automating repetitive tasks.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Consistency&lt;/strong&gt;: Ensures uniformity in testing across various API endpoints.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Scalability&lt;/strong&gt;: Makes it easier to scale tests as the system grows.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Integration&lt;/strong&gt;: Can be integrated into Continuous Integration (CI) and Continuous Deployment (CD) pipelines for continuous testing.&lt;/li&gt;
&lt;/ul&gt;

&lt;h3&gt;
  
  
  Using Swagger for API Testing
&lt;/h3&gt;

&lt;p&gt;&lt;strong&gt;Swagger&lt;/strong&gt; (now known as &lt;strong&gt;OpenAPI&lt;/strong&gt;) is one of the most widely used frameworks for defining and testing APIs. It allows developers to define their APIs in a standardized format, which can then be used for documentation and testing.&lt;/p&gt;

&lt;h3&gt;
  
  
  Example 1: Testing API with Swagger
&lt;/h3&gt;

&lt;p&gt;To test an API with Swagger, first define the API endpoints in a &lt;strong&gt;Swagger&lt;/strong&gt; (OpenAPI) specification file. Here's a simple example of how a user API might be defined in &lt;strong&gt;Swagger&lt;/strong&gt;:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight yaml"&gt;&lt;code&gt;&lt;span class="na"&gt;openapi&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;3.0.0&lt;/span&gt;
&lt;span class="na"&gt;info&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
  &lt;span class="na"&gt;title&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;User API&lt;/span&gt;
  &lt;span class="na"&gt;description&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;API for managing users in a system&lt;/span&gt;
  &lt;span class="na"&gt;version&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;1.0.0&lt;/span&gt;
&lt;span class="na"&gt;paths&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
  &lt;span class="s"&gt;/users/{id}&lt;/span&gt;&lt;span class="err"&gt;:&lt;/span&gt;
    &lt;span class="na"&gt;get&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
      &lt;span class="na"&gt;summary&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;Get a user by ID&lt;/span&gt;
      &lt;span class="na"&gt;parameters&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
        &lt;span class="pi"&gt;-&lt;/span&gt; &lt;span class="na"&gt;in&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;path&lt;/span&gt;
          &lt;span class="na"&gt;name&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;id&lt;/span&gt;
          &lt;span class="na"&gt;required&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="kc"&gt;true&lt;/span&gt;
          &lt;span class="na"&gt;schema&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
            &lt;span class="na"&gt;type&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;integer&lt;/span&gt;
            &lt;span class="na"&gt;example&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="m"&gt;1&lt;/span&gt;
      &lt;span class="na"&gt;responses&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
        &lt;span class="na"&gt;200&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
          &lt;span class="na"&gt;description&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;User found&lt;/span&gt;
          &lt;span class="na"&gt;content&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
            &lt;span class="na"&gt;application/json&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
              &lt;span class="na"&gt;schema&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
                &lt;span class="na"&gt;type&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;object&lt;/span&gt;
                &lt;span class="na"&gt;properties&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
                  &lt;span class="na"&gt;id&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
                    &lt;span class="na"&gt;type&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;integer&lt;/span&gt;
                  &lt;span class="na"&gt;name&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
                    &lt;span class="na"&gt;type&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;string&lt;/span&gt;
                &lt;span class="na"&gt;example&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
                  &lt;span class="na"&gt;id&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="m"&gt;1&lt;/span&gt;
                  &lt;span class="na"&gt;name&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;"&lt;/span&gt;&lt;span class="s"&gt;John&lt;/span&gt;&lt;span class="nv"&gt; &lt;/span&gt;&lt;span class="s"&gt;Doe"&lt;/span&gt;
        &lt;span class="na"&gt;404&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt;
          &lt;span class="na"&gt;description&lt;/span&gt;&lt;span class="pi"&gt;:&lt;/span&gt; &lt;span class="s"&gt;User not found&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;In this Swagger file, we've defined a GET request to retrieve a user by their ID.&lt;/p&gt;

&lt;h1&gt;
  
  
  Testing with Swagger Inspector
&lt;/h1&gt;

&lt;p&gt;You can use Swagger Inspector to validate the API by running tests directly from the Swagger specification.&lt;/p&gt;

&lt;p&gt;To use Swagger Inspector, simply enter the Swagger URL or upload the Swagger JSON/YAML file, and it will generate test requests for each defined endpoint.&lt;/p&gt;

&lt;h2&gt;
  
  
  Using JUnit and RestAssured for API Testing in Java
&lt;/h2&gt;

&lt;p&gt;&lt;strong&gt;JUnit&lt;/strong&gt; is one of the most widely used testing frameworks for Java. When combined with RestAssured, a library designed for testing REST APIs, JUnit provides a powerful solution for testing APIs in Java.&lt;/p&gt;

&lt;h3&gt;
  
  
  Example 2: Testing an API with JUnit and RestAssured
&lt;/h3&gt;

&lt;p&gt;First, add RestAssured and JUnit to your pom.xml:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight xml"&gt;&lt;code&gt;&lt;span class="nt"&gt;&amp;lt;dependency&amp;gt;&lt;/span&gt;
    &lt;span class="nt"&gt;&amp;lt;groupId&amp;gt;&lt;/span&gt;io.rest-assured&lt;span class="nt"&gt;&amp;lt;/groupId&amp;gt;&lt;/span&gt;
    &lt;span class="nt"&gt;&amp;lt;artifactId&amp;gt;&lt;/span&gt;rest-assured&lt;span class="nt"&gt;&amp;lt;/artifactId&amp;gt;&lt;/span&gt;
    &lt;span class="nt"&gt;&amp;lt;version&amp;gt;&lt;/span&gt;4.3.3&lt;span class="nt"&gt;&amp;lt;/version&amp;gt;&lt;/span&gt;
    &lt;span class="nt"&gt;&amp;lt;scope&amp;gt;&lt;/span&gt;test&lt;span class="nt"&gt;&amp;lt;/scope&amp;gt;&lt;/span&gt;
&lt;span class="nt"&gt;&amp;lt;/dependency&amp;gt;&lt;/span&gt;

&lt;span class="nt"&gt;&amp;lt;dependency&amp;gt;&lt;/span&gt;
    &lt;span class="nt"&gt;&amp;lt;groupId&amp;gt;&lt;/span&gt;org.junit.jupiter&lt;span class="nt"&gt;&amp;lt;/groupId&amp;gt;&lt;/span&gt;
    &lt;span class="nt"&gt;&amp;lt;artifactId&amp;gt;&lt;/span&gt;junit-jupiter-api&lt;span class="nt"&gt;&amp;lt;/artifactId&amp;gt;&lt;/span&gt;
    &lt;span class="nt"&gt;&amp;lt;version&amp;gt;&lt;/span&gt;5.7.0&lt;span class="nt"&gt;&amp;lt;/version&amp;gt;&lt;/span&gt;
    &lt;span class="nt"&gt;&amp;lt;scope&amp;gt;&lt;/span&gt;test&lt;span class="nt"&gt;&amp;lt;/scope&amp;gt;&lt;/span&gt;
&lt;span class="nt"&gt;&amp;lt;/dependency&amp;gt;&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Now, let's write a simple JUnit test to verify the GET request for the /users/{id} endpoint.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight java"&gt;&lt;code&gt;&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="nn"&gt;io.restassured.RestAssured&lt;/span&gt;&lt;span class="o"&gt;;&lt;/span&gt;
&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="nn"&gt;org.junit.jupiter.api.Test&lt;/span&gt;&lt;span class="o"&gt;;&lt;/span&gt;
&lt;span class="kn"&gt;import&lt;/span&gt; &lt;span class="nn"&gt;static&lt;/span&gt; &lt;span class="n"&gt;org&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;hamcrest&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;Matchers&lt;/span&gt;&lt;span class="o"&gt;.*;&lt;/span&gt;

&lt;span class="kd"&gt;public&lt;/span&gt; &lt;span class="kd"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;UserApiTest&lt;/span&gt; &lt;span class="o"&gt;{&lt;/span&gt;

    &lt;span class="nd"&gt;@Test&lt;/span&gt;
    &lt;span class="kd"&gt;public&lt;/span&gt; &lt;span class="kt"&gt;void&lt;/span&gt; &lt;span class="nf"&gt;testGetUser&lt;/span&gt;&lt;span class="o"&gt;()&lt;/span&gt; &lt;span class="o"&gt;{&lt;/span&gt;
        &lt;span class="nc"&gt;RestAssured&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;baseURI&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="s"&gt;"https://reqres.in/api"&lt;/span&gt;&lt;span class="o"&gt;;&lt;/span&gt; &lt;span class="c1"&gt;// Base URL&lt;/span&gt;

        &lt;span class="nc"&gt;RestAssured&lt;/span&gt;
            &lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;given&lt;/span&gt;&lt;span class="o"&gt;()&lt;/span&gt;
                &lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;pathParam&lt;/span&gt;&lt;span class="o"&gt;(&lt;/span&gt;&lt;span class="s"&gt;"id"&lt;/span&gt;&lt;span class="o"&gt;,&lt;/span&gt; &lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="o"&gt;)&lt;/span&gt; &lt;span class="c1"&gt;// Path parameter&lt;/span&gt;
            &lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;when&lt;/span&gt;&lt;span class="o"&gt;()&lt;/span&gt;
                &lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;get&lt;/span&gt;&lt;span class="o"&gt;(&lt;/span&gt;&lt;span class="s"&gt;"/users/{id}"&lt;/span&gt;&lt;span class="o"&gt;)&lt;/span&gt; &lt;span class="c1"&gt;// GET request to /users/{id}&lt;/span&gt;
            &lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;then&lt;/span&gt;&lt;span class="o"&gt;()&lt;/span&gt;
                &lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;statusCode&lt;/span&gt;&lt;span class="o"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;200&lt;/span&gt;&lt;span class="o"&gt;)&lt;/span&gt; &lt;span class="c1"&gt;// Assert that the status code is 200 (OK)&lt;/span&gt;
                &lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;body&lt;/span&gt;&lt;span class="o"&gt;(&lt;/span&gt;&lt;span class="s"&gt;"data.id"&lt;/span&gt;&lt;span class="o"&gt;,&lt;/span&gt; &lt;span class="n"&gt;equalTo&lt;/span&gt;&lt;span class="o"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="o"&gt;))&lt;/span&gt; &lt;span class="c1"&gt;// Validate that the ID is 1&lt;/span&gt;
                &lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="na"&gt;body&lt;/span&gt;&lt;span class="o"&gt;(&lt;/span&gt;&lt;span class="s"&gt;"data.first_name"&lt;/span&gt;&lt;span class="o"&gt;,&lt;/span&gt; &lt;span class="n"&gt;equalTo&lt;/span&gt;&lt;span class="o"&gt;(&lt;/span&gt;&lt;span class="s"&gt;"George"&lt;/span&gt;&lt;span class="o"&gt;));&lt;/span&gt; &lt;span class="c1"&gt;// Validate first_name&lt;/span&gt;
    &lt;span class="o"&gt;}&lt;/span&gt;
&lt;span class="o"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;In this example:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;RestAssured&lt;/strong&gt; is used to send a &lt;strong&gt;GET&lt;/strong&gt; request to the /users/{id} endpoint.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;JUnit&lt;/strong&gt; is used to validate that the response code is 200 and that the returned ID and first_name match the expected values.&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;&lt;strong&gt;Step 3: Running the Test&lt;/strong&gt;&lt;br&gt;
You can run the test using Maven:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight shell"&gt;&lt;code&gt;mvn &lt;span class="nb"&gt;test&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;This will execute the test, and JUnit will validate the response based on the conditions defined in the test.&lt;/p&gt;

&lt;h1&gt;
  
  
  Integrating API Tests into CI/CD Pipelines
&lt;/h1&gt;

&lt;p&gt;Integrating API tests into your CI/CD pipeline ensures that your tests run automatically with each code change. This helps identify issues early in the development process.&lt;/p&gt;

&lt;h1&gt;
  
  
  Integrating with Jenkins
&lt;/h1&gt;

&lt;p&gt;To run the JUnit tests in Jenkins, you can add the following steps to your Jenkinsfile:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight groovy"&gt;&lt;code&gt;&lt;span class="n"&gt;pipeline&lt;/span&gt; &lt;span class="o"&gt;{&lt;/span&gt;
    &lt;span class="n"&gt;agent&lt;/span&gt; &lt;span class="n"&gt;any&lt;/span&gt;
    &lt;span class="n"&gt;stages&lt;/span&gt; &lt;span class="o"&gt;{&lt;/span&gt;
        &lt;span class="n"&gt;stage&lt;/span&gt;&lt;span class="o"&gt;(&lt;/span&gt;&lt;span class="s1"&gt;'Build'&lt;/span&gt;&lt;span class="o"&gt;)&lt;/span&gt; &lt;span class="o"&gt;{&lt;/span&gt;
            &lt;span class="n"&gt;steps&lt;/span&gt; &lt;span class="o"&gt;{&lt;/span&gt;
                &lt;span class="n"&gt;sh&lt;/span&gt; &lt;span class="s1"&gt;'mvn clean install'&lt;/span&gt;
            &lt;span class="o"&gt;}&lt;/span&gt;
        &lt;span class="o"&gt;}&lt;/span&gt;
        &lt;span class="n"&gt;stage&lt;/span&gt;&lt;span class="o"&gt;(&lt;/span&gt;&lt;span class="s1"&gt;'Test'&lt;/span&gt;&lt;span class="o"&gt;)&lt;/span&gt; &lt;span class="o"&gt;{&lt;/span&gt;
            &lt;span class="n"&gt;steps&lt;/span&gt; &lt;span class="o"&gt;{&lt;/span&gt;
                &lt;span class="n"&gt;sh&lt;/span&gt; &lt;span class="s1"&gt;'mvn test'&lt;/span&gt; &lt;span class="c1"&gt;// Run JUnit tests&lt;/span&gt;
            &lt;span class="o"&gt;}&lt;/span&gt;
        &lt;span class="o"&gt;}&lt;/span&gt;
    &lt;span class="o"&gt;}&lt;/span&gt;
&lt;span class="o"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;This Jenkins pipeline will trigger the JUnit tests automatically every time code is committed to your repository.&lt;/p&gt;

&lt;h3&gt;
  
  
  Running Swagger Tests in CI/CD
&lt;/h3&gt;

&lt;p&gt;You can also integrate Swagger Inspector in a CI/CD pipeline by calling the Swagger API using a curl command in your pipeline to validate the API against your Swagger definitions.&lt;/p&gt;

&lt;h1&gt;
  
  
  Best Practices for API Testing
&lt;/h1&gt;

&lt;p&gt;When applying frameworks for API testing, consider the following best practices:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt;
&lt;strong&gt;Organize Your Tests&lt;/strong&gt;: Group your tests by API category or functionality for easier maintenance.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Use Data-Driven Testing&lt;/strong&gt;: Test different data sets to ensure the API behaves correctly with a variety of inputs.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Mock APIs&lt;/strong&gt;: Use mock servers to simulate APIs during testing, especially when the actual API is not available.&lt;/li&gt;
&lt;li&gt;
&lt;strong&gt;Automate Your Tests&lt;/strong&gt;: Automate your API tests and integrate them into the CI/CD pipeline for continuous testing.&lt;/li&gt;
&lt;/ol&gt;

&lt;h2&gt;
  
  
  Conclusion
&lt;/h2&gt;

&lt;p&gt;API testing is an essential part of ensuring the functionality, security, and performance of your APIs. By using Swagger for API documentation and JUnit with RestAssured for testing, you can streamline the testing process and ensure that your APIs are thoroughly tested.&lt;/p&gt;

&lt;p&gt;Integrating these tools into your CI/CD pipeline allows for continuous testing, ensuring your APIs remain reliable and meet the expected requirements.&lt;/p&gt;

&lt;h2&gt;
  
  
  References
&lt;/h2&gt;

&lt;p&gt;&lt;a href="https://swagger.io/docs/" rel="noopener noreferrer"&gt;Swagger Documentation&lt;/a&gt;&lt;br&gt;
&lt;a href="https://junit.org/" rel="noopener noreferrer"&gt;JUnit 5 Documentation&lt;/a&gt;&lt;br&gt;
&lt;a href="https://rest-assured.io/" rel="noopener noreferrer"&gt;RestAssured Documentation&lt;/a&gt;&lt;br&gt;
&lt;a href="https://alicealdaine.medium.com/top-10-api-testing-tools-rest-soap-services-5395cb03cfa9" rel="noopener noreferrer"&gt;Top 15 API Testing Tools in 2022&lt;/a&gt;&lt;/p&gt;

</description>
      <category>webdev</category>
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    </item>
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