Debug mode error pages in Flask - Mini Project: Build & Apply

Debug Mode Error Pages in Flask

📖 Scenario: You are building a simple Flask web app. You want to see detailed error pages when something goes wrong during development. This helps you find and fix bugs faster.

🎯 Goal: Create a Flask app that shows debug mode error pages when an error happens. You will set up the app, enable debug mode, create a route that causes an error, and run the app so you can see the detailed error page.

📋 What You'll Learn

Create a Flask app instance named app

Enable debug mode by setting app.debug = True

Create a route /cause-error that raises a ZeroDivisionError

Run the app with app.run() so debug mode error pages appear

💡 Why This Matters

🌍 Real World

Developers use debug mode error pages to quickly find and fix bugs during app development.

💼 Career

Understanding debug mode is essential for backend developers working with Flask to build reliable web applications.

1

Create the Flask app instance

Import Flask from flask and create a Flask app instance called app.

Flask

from flask import Flask

# Create the Flask app instance called app
# Your code here

Need a hint?

Use Flask(__name__) to create the app instance.

2

Enable debug mode

Set the debug attribute of the app instance to True to enable debug mode.

Flask

from flask import Flask

app = Flask(__name__)

# Enable debug mode
# Your code here

Need a hint?

Set app.debug = True to turn on debug mode.

3

Create a route that causes an error

Define a route /cause-error using @app.route. Inside the view function cause_error, raise a ZeroDivisionError by dividing 1 by 0.

Flask

from flask import Flask

app = Flask(__name__)

app.debug = True

# Create a route /cause-error that raises ZeroDivisionError
# Your code here

Need a hint?

Use @app.route('/cause-error') and define cause_error() that returns 1 / 0.

4

Run the Flask app

Add the code to run the Flask app by calling app.run() at the bottom of the file.

Flask

from flask import Flask

app = Flask(__name__)

app.debug = True

@app.route('/cause-error')
def cause_error():
    return 1 / 0

# Run the app
# Your code here

Need a hint?

Call app.run() to start the Flask development server.