How to Build a Flask Python Web Application?

Have you ever wanted to build your own web application but didn’t know where to start? Flask, a lightweight and easy-to-use Python web framework, is the perfect choice for beginners and experienced developers alike. Whether you want to create a personal blog, a portfolio site, or even a data-driven web app, Flask has got you covered. In this guide, we’ll walk you through the entire process of building a simple yet functional web application using Flask.

What is Flask?

Flask is a micro web framework written in Python. Unlike Django, which comes with many built-in features, Flask is minimalistic and gives you full control over your application. Here are some key advantages of using Flask:

• Lightweight & Flexible: You only add the components you need.
• Easy to Learn: Simple syntax and minimal boilerplate.
• Scalable: Suitable for small projects and large applications.
• Extensible: Easily integrates with databases, APIs, and other tools.

Prerequisites

Before we dive into coding, make sure you have the following installed:

• Python (Version 3.x recommended)
• Flask Framework – Install using pip install flask
• A Code Editor – VS Code, PyCharm, or any text editor of your choice
• Basic Knowledge of Python

How to Build a Flask Python Web Application?

Step 1: Setting Up Your Flask Project

1.1 Create a New Project Directory

First, create a new folder for your Flask project and navigate into it using the terminal:

1.2 Create a Virtual Environment (Optional but Recommended)

Virtual environments help manage dependencies efficiently. Run the following command:

1.3 Install Flask

Now, install Flask inside the virtual environment:

2.1 Writing Your First Flask Application

Inside your project folder, create a new file named app.py and add the following code:

2.2 Running the Application

Save the file and run the following command in the terminal:

You should see an output like this:

Step 3: Adding HTML Templates

Flask allows you to render HTML templates using Jinja2, a powerful templating engine. Let’s create a basic HTML page.

3.1 Create a templates Folder

Inside your project directory, create a folder named templates. Then, create a file named index.html inside templates and add the following code:

3.2 Modify app.py to Render the Template

Update your app.py file to use the template:

Run the application again and refresh your browser. You should see the rendered HTML page!

Step 4: Adding Dynamic Routes and Forms

Flask allows you to handle dynamic routes and user input using forms.

4.1 Creating a Dynamic Route

Modify app.py to include a dynamic route:

4.2 Handling Forms

Step 5: Deploying Your Flask App

Once you’re happy with your Flask app, you might want to deploy it online. Popular options include:

• Heroku (Free tier available)
• PythonAnywhere
• AWS, Google Cloud, or Azure
• To deploy on Heroku, follow these steps:

Conclusion

Congratulations! You’ve just built and deployed a Flask web application from scratch. With Flask, the possibilities are endless. You can integrate databases, authentication, APIs, and more. Keep experimenting, and soon, you’ll be building full-fledged web applications effortlessly!

If you found this guide helpful, don’t forget to share it with others who want to learn Flask. Happy coding!