Welcome to our first lesson on authentication with Flask!
Today, we'll learn how to build a simple login system for our web application. This lesson is foundational because login systems are crucial for almost any web app that handles user data or personalized experiences.
By the end of this unit, you'll be able to create an endpoint that accepts login credentials, validates them, and responds accordingly.
Before we dive into building the login endpoint, let's set up our application and mock database.
This code initializes a Flask app and creates a mock dataset that we'll use for authentication.
To ensure the login credentials are in the correct format, we'll use Marshmallow to help us validate and deserialize input data.
Let's create a simple schema for our login data with username and password:
In this schema, we define username and password as required string fields, and use Length(min=1) to ensure both fields are not empty.
Now, let's create the /login endpoint in our Flask application. This is where users will send their login credentials.
To validate the incoming data from the request we will use the LoginSchema we previously defined.
We can now extract the username and password from the validated data and check for the given username in our database.
Finally, once we know the user exists, we check if the given password matches with the one in the database. Then respond accordingly.
When the client sends a POST request to /login with correct credentials, they should receive a 200 OK response with a message indicating a successful login:
However, if the client provides incorrect credentials, they will receive a 401 Unauthorized response indicating a bad username or password:
Additionally, if the request fails validation, such as missing required fields, the client will receive a 400 Bad Request response with error details:
In this lesson, we learned to create a basic login endpoint using Flask by covering how to:
- Validate data to ensure login credentials are well-formed.
- Create a
/loginendpoint to accept, validate, and authenticate user credentials. - Handle errors with appropriate responses for validation failures and incorrect login attempts.
Next, you'll put this knowledge into practice by creating and testing your own login endpoint. In upcoming lessons, we'll explore JWT (JSON Web Token) authentication to further secure our application. Stay tuned and continue practicing!
