Setting and reading cookies in Flask - Mini Project: Build & Apply

Setting and reading cookies in Flask

📖 Scenario: You are building a simple web app that remembers a visitor's favorite color using cookies.This helps the site greet them with their chosen color every time they visit.

🎯 Goal: Create a Flask app that sets a cookie named favorite_color when the user visits the /set_color route with a color query parameter.Then, read that cookie on the /show_color route and display a message with the stored color.

📋 What You'll Learn

Create a Flask app with two routes: /set_color and /show_color

In /set_color, set a cookie named favorite_color with the color from the query parameter

In /show_color, read the favorite_color cookie and display it in the response

Use Flask's make_response to set cookies

Handle the case where the cookie is not set by showing a default message

💡 Why This Matters

🌍 Real World

Websites often use cookies to remember user preferences like themes, languages, or login sessions to improve user experience.

💼 Career

Understanding how to set and read cookies is essential for backend web developers to manage user sessions and preferences securely.

1

Create the Flask app and import modules

Write code to import Flask, request, and make_response from flask. Then create a Flask app instance called app.

Flask

# Import Flask, request, and make_response from flask
# Create a Flask app instance named app
# Your code here

Need a hint?

Use from flask import Flask, request, make_response and then app = Flask(__name__).

2

Create the /set_color route to set the cookie

Define a route /set_color using @app.route. Inside the function set_color(), get the query parameter color from request.args. Use make_response to create a response with the text "Color set to {color}". Then set a cookie named favorite_color with the value of color on the response. Return the response.

Flask

from flask import Flask, request, make_response

app = Flask(__name__)

# Define /set_color route to set favorite_color cookie
# Your code here

Need a hint?

Use request.args.get('color') to get the color. Use make_response to create the response and response.set_cookie to set the cookie.

3

Create the /show_color route to read the cookie

Define a route /show_color using @app.route. Inside the function show_color(), read the cookie named favorite_color from request.cookies. If the cookie exists, return the text "Your favorite color is {color}". Otherwise, return "No favorite color set."

Flask

from flask import Flask, request, make_response

app = Flask(__name__)

@app.route('/set_color')
def set_color():
    color = request.args.get('color')
    response = make_response(f"Color set to {color}")
    response.set_cookie('favorite_color', color)
    return response

# Define /show_color route to read favorite_color cookie
# Your code here

Need a hint?

Use request.cookies.get('favorite_color') to read the cookie. Use an if-else to return the correct message.

4

Add the app run block

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

Flask

from flask import Flask, request, make_response

app = Flask(__name__)

@app.route('/set_color')
def set_color():
    color = request.args.get('color')
    response = make_response(f"Color set to {color}")
    response.set_cookie('favorite_color', color)
    return response

@app.route('/show_color')
def show_color():
    color = request.cookies.get('favorite_color')
    if color:
        return f"Your favorite color is {color}"
    else:
        return "No favorite color set."

# Add the app run block below
# Your code here

Need a hint?

Use the standard Flask run block with debug=true for easier testing.