How Your Browser Uses Cookies: A Simple Guide to Cookie Management in Flask

Cookies are small pieces of data stored on the client side, which can be used to track user sessions, maintain user preferences, and more. In Flask, cookies can be easily managed using its built-in functionality. In this blog, we’ll dive deep into how cookies work in Flask, how to set, get, and delete them, and we’ll illustrate it with practical examples.

What are Cookies?

Cookies are simple text files sent from a web server to a client browser. They are saved on the client’s computer and contain small pieces of data that are used for various purposes, such as remembering login states, tracking user activities, and maintaining user preferences.

A cookie typically contains:

• Name: The name of the cookie.
• Value: The actual data.
• Domain: The domain for which the cookie is valid.
• Path: The path in the domain where the cookie is accessible.
• Expiration: When the cookie expires (optional).
• Secure/HttpOnly Flags: Additional security flags.

Cookies in Flask

Flask makes it very simple to set, retrieve, and delete cookies. Flask’s Response and request objects handle these operations.

Let’s explore the essential operations for working with cookies in Flask.

Setting a Cookie in Flask

To set a cookie, you can use the set_cookie() method of the Response object. You generally create a response and then attach a cookie to it.

Here’s an example:

from flask import Flask, request, make_response

app = Flask(__name__)

@app.route('/setcookie')
def set_cookie():
    # Create a response object
    response = make_response("Cookie is set!")
    
    # Set a cookie named…