Development server with debug mode in Flask - Mini Project: Build & Apply

Development server with debug mode

📖 Scenario: You are creating a simple Flask web application to test your code changes quickly. You want to set up the Flask development server so it automatically reloads when you make changes and shows detailed error messages.

🎯 Goal: Build a Flask app that runs with debug mode enabled, so you can see errors and have the server reload automatically during development.

📋 What You'll Learn

Create a Flask app instance named app

Define a route / that returns the text 'Hello, Flask!'

Add a variable debug_mode set to True

Run the Flask app with debug mode enabled using app.run(debug=debug_mode)

💡 Why This Matters

🌍 Real World

Developers use Flask's debug mode to speed up development by seeing errors immediately and not restarting the server manually.

💼 Career

Knowing how to run Flask apps in debug mode is essential for backend web development and testing.

1

Create the Flask app and a basic route

Import Flask from flask. Create a Flask app instance called app. Define a route for '/' that returns the string 'Hello, Flask!'.

Flask

from flask import Flask

# Create the Flask app instance
# Your code here

Need a hint?

Use app = Flask(__name__) to create the app. Use @app.route('/') to define the home page route.

2

Add a debug mode variable

Create a variable called debug_mode and set it to True to enable debug mode.

Flask

from flask import Flask

app = Flask(__name__)

debug_mode = False  # Set debug mode variable here

@app.route('/')
def home():
    return 'Hello, Flask!'

Need a hint?

Just write debug_mode = True to enable debug mode.

3

Run the Flask app with debug mode

Add the code to run the Flask app only if the script is run directly. Use app.run(debug=debug_mode) to start the server with debug mode enabled.

Flask

from flask import Flask

app = Flask(__name__)

debug_mode = True

@app.route('/')
def home():
    return 'Hello, Flask!'

# Run the app with debug mode
# Your code here

Need a hint?

Use the if __name__ == '__main__': guard to run the app. Pass debug=debug_mode to app.run().

4

Complete the Flask app with debug mode enabled

Ensure the full code includes the import, app creation, route, debug_mode variable, and the run command with debug mode enabled.

Flask

from flask import Flask

app = Flask(__name__)

debug_mode = True

@app.route('/')
def home():
    return 'Hello, Flask!'

if __name__ == '__main__':
    # Run the app with debug mode enabled
    # Your code here

Need a hint?

Check that all parts are included and the app runs with debug mode enabled.