Building a Simple Web Application with Python Flask

Python Flask is a lightweight web framework that is simple, flexible, and suitable for building web applications of various scales.

Part 1: Set up the development environment

Ensure Python and pip are installed, then run the following command to install Flask:

pip install flask

Part 2: Create the Flask application

Create a file named app.py and add the following code to import Flask and create an app instance:

from flask import Flask

app = Flask(__name__)

Define a route and view function that returns a simple string:

@app.route('/')

def index():

return 'Hello, Flask!'

Part 3: Run the Flask application

Add the entry point at the end of app.py :

if __name__ == '__main__':

app.run()

Start the server from the command line:

python app.py

The console will display a message such as Running on http://127.0.0.1:5000/ , indicating the app is listening on port 5000.

Part 4: Access the application

Open a web browser and navigate to http://127.0.0.1:5000/ ; you should see the text "Hello, Flask!".

Part 5: Add more features – Form handling

Flask can process user‑submitted forms. Create an HTML <form> with method="POST" and action="/login" , then define a /login route that uses request.form.get() to retrieve and validate the submitted data.

Part 6: Database integration

To integrate MySQL, import the MySQL driver, configure the connection, and create a helper function such as get_db_connection() . Use the connection inside view functions to execute queries and return results, then run the app as before.

Remember to adjust the database connection parameters (host, user, password, database) and install the required driver (e.g., mysql-connector-python ).