Route with dynamic parameters in Flask - Mini Project: Build & Apply

Flask Route with Dynamic Parameters

📖 Scenario: You are building a simple web app using Flask. You want to create a route that can accept a dynamic username in the URL and greet that user personally.

🎯 Goal: Build a Flask app with a route that uses a dynamic parameter called username in the URL path. When a user visits /hello/<username>, the app should greet them by name.

📋 What You'll Learn

Create a Flask app instance named app

Define a route with the URL pattern /hello/<username>

Create a view function named hello_user that accepts username as a parameter

Return a greeting string that includes the username

💡 Why This Matters

🌍 Real World

Web apps often need to handle user-specific pages or data by capturing parts of the URL dynamically.

💼 Career

Understanding dynamic routes is essential for backend web development roles using Flask or similar frameworks.

1

Create the Flask app instance

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

Flask

# Your code here

Need a hint?

Use Flask(__name__) to create the app instance.

2

Define the route with dynamic parameter

Use the @app.route decorator to define a route with the URL pattern /hello/<username>.

Flask

from flask import Flask
app = Flask(__name__)

# Your code here

Need a hint?

Use angle brackets <> around username in the route URL.

3

Create the view function to accept the parameter

Define a function named hello_user that takes username as a parameter and returns a greeting string including the username.

Flask

from flask import Flask
app = Flask(__name__)

@app.route('/hello/')
# Your code here

Need a hint?

Use an f-string to include username in the returned greeting.

4

Add the app run command

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

Flask

from flask import Flask
app = Flask(__name__)

@app.route('/hello/')
def hello_user(username):
    return f"Hello, {username}!"

# Your code here

Need a hint?

This block ensures the app runs only when the script is executed directly.