flask authentication user without database

To implement user authentication without a database in Flask, you can use a combination of its built-in session and a custom user class. First, you'll need to create a user class that represents the authenticated user. Then, you can use Flask's session to store the user's information securely. When the user logs in, you can store the user's ID in the session, and when the user logs out, you can remove the user's ID from the session. Here are the steps to achieve this:

1. Create a user class with properties such as username, password, and any other relevant information.

2. Implement a login route where the user can submit their credentials. Verify the credentials and if they are correct, store the user's ID in the session.

3. Implement a logout route to remove the user's ID from the session, effectively logging them out.

4. Use the session to check if a user is logged in on each request, and if so, retrieve the user's information using the stored ID.

By following these steps, you can implement user authentication in Flask without the need for a traditional database.