DEV Community: priyanshu pardhi

Beginners Guide to environment variable setup (Django)

priyanshu pardhi — Sat, 02 Sep 2023 09:35:18 +0000

FYI: Python virtual environment and environment variables is two different things.

We are going to talk about setting up environment variables.
Whenever we create an app there are some secret credential throughout our application that need to be secured.
For securing an app we keep such credentials in an environment variable (Ideally we should do it before pushing and sharing to any remote resource).

Installation

1. Install Django Environ

In your terminal, inside the project directory, type:

$ pip install django-environ

2. Import environ

Inside setting.py

import environ

3. Initialise environ

Below your import in settings.py:

import environ
# Initialise environment variables
env = environ.Env()
environ.Env.read_env()

4. Create your .env file

In the same directory as settings.py, create a file called .env, keep the essential and secured credential there, below we have added some common environment variable

SERVER=dev
DEBUG=True
SECRET_KEY=<project's secret key>

ALLOWED_HOSTS=['*']                # where '*' represents a wild-card to accept any HTTP host value.

# Database setting
DB_NAME=
DB_USER=
DB_PASSWORD=
DB_HOST=
DB_PORT=

5. Replace all references to your environment variables in settings.py

since we have mentioned these environment variable here, we need a way to access this variables wherever we are using these variables, for that we need to replace all references to your environment variables in settings.py

...
import os
from pathlib import Path
import environ
.
.
env = environ.Env(DEBUG=bool, ALLOWED_HOSTS=list)
env_file = BASE_DIR / '.env'               # path to your .env file

environ.Env.read_env(env_file=env_file, overwrite=True)
...
SECRET_KEY = env('SECRET_KEY')
...
DEBUG = env('DEBUG')
...
ALLOWED_HOSTS = env('ALLOWED_HOSTS')
...
if DEBUG:
    DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.sqlite3',
            'NAME': BASE_DIR / 'db.sqlite3',
        }
    }
else:
    DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.postgresql_psycopg2',
            'NAME': env('DB_NAME'),
            'USER': env('DB_USER'),
            'PASSWORD': env('DB_PASSWORD'),
            'HOST': env('DB_HOST'),
            'PORT': env('DB_PORT'),
        }
    }

IMPORTANT: Add your .env file to .gitignore

Now you are ready to push your code 🚀.

Reference

How to set up environment variables in Django

Feel free to share! 👍

Build a web-app with servlet

priyanshu pardhi — Fri, 15 Jul 2022 11:13:11 +0000

Topics covered

Calling a servlet from a html page
Making a servlet ( a class which extends HttpServlet )
Getting values from the html page using HttpServletRequest and HttpServletResponse
Mapping servlet class
doPost() method

Make a simple web-app with servlet
we are going to make an app which adds two numbers.

Prerequisite: Basic knowledge about Java.

IDE (preferably Eclipse for Java EE Developers).
Web Server (preferably Tomcat).

Step 0: Before making the project, let's configure tomcat server.

If you don't see server tab in the bottom panel.

go to Window ( in the navigation bar ).
click on show view
click on server

Now you get server in the bottom panel, click to configure tomcat, (you need to download the tomcat core and source code and unzip the files) select the version and path.

If you want to check you can go to http:8080

Now server is configured.

Step 1: Start Eclipse, Open a new "Dynamic Webapp" Project.

as shown below.

Create a package com.app

Step 2: Create a HTML file where you will write the HTML code.

Make a simple form with two input the first one is for 1st no. & 2nd for 2nd no and one submit button.
In HTML form, inside the form tag define action attribute and assign the add path to it i.e action="add”.

<form method="get" action="add">
  Enter 1st no.  <input type="text" name="num1"><br>
  Enter 2nd no. <input type="text" name="num2"><br>
 <button >Submit</button>
</form>

Step 3: Create a Servlet or a class which extends HttpServlet (import necessary packages)

Define a service method which takes two parameters HttpServletRequest as req and HttpServletRespone as res.
Now write the logic for addition of two numbers inside the method

int i = Integer.parseInt(req.getParameter("num1"));
int j = Integer.parseInt(req.getParameter("num2"));  

int k = i+j;

//Print the out put
PrintWriter out = res.getWriter();
out.println(k);

But wait a minute, server doesn’t know which servlet to call so it will give an error.

Step 4: This can be resolved by mapping the HTML page with servlet, for that we will use “web.xml” or deployment descriptor file.

<servlet>
   <servlet-name>My servlet</servlet-name>
   <servlet-class>com.app.AppServlet</servlet-class>
</servlet>
<servlet-mapping>
   <servlet-name>My servlet</servlet-name>
   <url-pattern>/add</url-pattern>
</servlet-mapping>

Now start the server and input two no and submit

and you got the answer 👍

But again there is one problem over here the data which we are sending is exposed in url, is there any method to hide that & why it is exposed?

It’s because the form default method is “get” we need to convert that to “post” i.e. method=”post”.

However you can change HTTP method parameter from browser inspect tool, so to solve the problem totally we need to change the method in servlet instead of using service method we will use doPost method for post method. This will solve the problem.

Source code: https://github.com/priyanshupardhi/ServletApp

🎉Hurray!🎉 you just created your first Web App using Servlet

What is Maven?

priyanshu pardhi — Tue, 21 Jun 2022 08:55:46 +0000

Maven is project management tool.

In java, whenever you want to make a project you need lots of third party libraries such as MySql connector.

If you are not using maven in your project you need to download lots of external jar files and manually configure those into your project also updating that is a tiresome process that’s why we need maven which make developer’s life easier

A maven project basically consist of :-

POM file

In which we have :-

Group ID (let say “com.app”), define your package
Artifact ID (let say “demo”), represent your project name
Package (com.app.demo.web)

How do you mention in the pom.xml file that I want this dependency in my project? for that you need to add XML code for that dependency

To get the xml code for a particular module:

just go to MVN Repository
Search for desired module
Select the available version, check xml code for that module/ dependency

When you are working with maven you need to have internet connection

If you are using any dependency for the first time.

First, it will check for that dependencies in Local Repo, if not found, it will check download/fetch from Remote Repo

Alternate of Maven is Gradle

Thanks for reading

What is servlet?

priyanshu pardhi — Wed, 06 Apr 2022 13:44:25 +0000

What is Servlet?

Imagine we have a client machine and a server. Client requests the server for a page (let's say). Now this page could be static, or it could be dynamic (built at runtime). When client requests the server, it will be like I don't have any page, so you have to build that web page at runtime, than the request goes to an helper application also know as Web Container, e.g. Tomcat, JBoss, Websphere, etc).

Web Container contains "Servlet", a java file which can take the request from client on the internet, process it and respond with a response as a HTML page. Servlet will convert the client request, fetch the values, process the information and return a HTML page.

Web Container also contains “Deployment Descriptor”, a simple XML document that is used to map URL to the servlet.

But how do you create a servlet?

A servlet is a normal java class which extends HttpServlet, since we want this servlet features ( request, process, response ) the response from servlet will be in HTML format (you can also send the response in JSON/XML format) now that HTML page will go from your server to client machine in the format of Response Object.

CODE JOURNAL

priyanshu pardhi — Sun, 03 Jan 2021 07:00:58 +0000

This journal can be used for taking notes in class or to record snippets of code you will be using frequently.

Personal Site: CODE JOURNAL

A blog where you can share your learning during #100DaysOfCode.

How I built it
I'll be using HTML,CSS,JS AND NODE.JS.

DAY 1 of Hackathon