URL building with url_for in Flask - Mini Project: Build & Apply

URL building with url_for in Flask

📖 Scenario: You are creating a simple Flask web app that has multiple pages. You want to build URLs dynamically using Flask's url_for function instead of hardcoding links. This helps keep your app flexible and easy to maintain.

🎯 Goal: Build a Flask app with two routes: / and /about. Use url_for to generate the URL for the about page inside the home page's HTML link.

📋 What You'll Learn

Create a Flask app with two routes: home and about

Use url_for inside the home route to build the URL for the about page

Return simple HTML strings from both routes

The home page should have a link to the about page using the URL built by url_for

💡 Why This Matters

🌍 Real World

Web developers use url_for to build URLs dynamically so links stay correct even if routes change. This avoids hardcoding URLs and reduces bugs.

💼 Career

Understanding url_for is essential for Flask developers to write maintainable and flexible web applications.

1

Set up the Flask app and home route

Import Flask from flask. Create a Flask app called app. Define a route for / with a function called home that returns the string 'Home Page'.

Flask

# Your code here

Need a hint?

Start by importing Flask and creating the app instance. Then add a route for the home page that returns a simple string.

2

Add the about route

Define a new route for /about with a function called about that returns the string 'About Page'.

Flask

from flask import Flask

app = Flask(__name__)

@app.route('/')
def home():
    return 'Home Page'

# Your code here

Need a hint?

Add a new route for the about page that returns a simple string.

3

Import url_for and build URL in home route

Import url_for from flask. Inside the home function, use url_for('about') to get the URL for the about page. Return an HTML string with an anchor tag linking to this URL and the text 'About'.

Flask

from flask import Flask

app = Flask(__name__)

@app.route('/')
def home():
    # Use url_for to build the about page URL
    # Your code here

@app.route('/about')
def about():
    return 'About Page'

Need a hint?

Import url_for and use it inside the home function to create a link to the about page.

4

Add app run block

Add the standard Flask app run block at the bottom: if __name__ == '__main__': and inside it call app.run(debug=True).

Flask

from flask import Flask, url_for

app = Flask(__name__)

@app.route('/')
def home():
    about_url = url_for('about')
    return f'About'

@app.route('/about')
def about():
    return 'About Page'

# Your code here

Need a hint?

Add the block to run the Flask app when the script is executed directly.