Application context in Flask - Mini Project: Build & Apply

Understanding Flask Application Context

📖 Scenario: You are building a simple Flask web app that needs to access the application context to store and retrieve data during a request.

🎯 Goal: Learn how to use Flask's application context to store a variable and access it inside a route function.

📋 What You'll Learn

Create a Flask app instance

Use the application context to store a variable

Access the stored variable inside a route

Return the stored variable as a response

💡 Why This Matters

🌍 Real World

Flask application context is used to store data that should be accessible globally during the app's runtime, such as configuration or database connections.

💼 Career

Understanding Flask application context is essential for backend web developers working with Flask to manage app-wide data safely and effectively.

1

Create a Flask app instance

Write code to import Flask from flask and create a Flask app instance called app.

Flask

# Import Flask and create app instance
# Your code here

Need a hint?

Use Flask(__name__) to create the app instance.

2

Push the application context and set a variable

Write code to push the application context using app.app_context().push() and then set a variable app.config['MY_VAR'] to the string 'Hello Context'.

Flask

from flask import Flask
app = Flask(__name__)

# Push app context and set MY_VAR
# Your code here

Need a hint?

Use app.app_context().push() to activate the context before setting the config variable.

3

Create a route that accesses the context variable

Write a route function using @app.route('/') that returns the value of app.config['MY_VAR'] as the response string.

Flask

from flask import Flask
app = Flask(__name__)

app.app_context().push()
app.config['MY_VAR'] = 'Hello Context'

# Create route '/' that returns app.config['MY_VAR']
# Your code here

Need a hint?

Define a function named home decorated with @app.route('/') that returns the stored variable.

4

Add the app run command

Write code to run the Flask app with app.run() inside a if __name__ == '__main__': block.

Flask

from flask import Flask
app = Flask(__name__)

app.app_context().push()
app.config['MY_VAR'] = 'Hello Context'

@app.route('/')
def home():
    return app.config['MY_VAR']

# Add app.run() inside main guard
# Your code here

Need a hint?

Use the standard Python main guard to run the app.