The class and method for login are similar to those for registration. Let's write it:
``` python
@blp.route("/login")
class UserLogin(MethodView):
    @blp.arguments(UserSchema)
    def post(self, user_data):
        user = UserModel.query.filter(
            UserModel.username == user_data["username"]
        ).first()

        if user and pbkdf2_sha256.verify(user_data["password"], user.password):
            access_token = create_access_token(identity=user.id)
            return {"access_token": access_token}, 200

        abort(401, message="Invalid credentials.")
```

We filter users in the database by username and check if such a user exists and if the password verification for this user passes. If so, we create a JWT access token.

In this method, we return an access token generated using the `create_access_token` function imported from the `flask_jwt_extended` library. We add the user ID information to the JWT access token so that when a user returns the JWT to us, we will know which user it belongs to.

If a user with the given username does not exist or the password does not match what is in the table, we return an error.

Which HTTP method is used by the UserLogin class to authenticate users?

What information is included in the JWT access token generated by the UserLogin method?

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Login Endpoint

1. Which HTTP method is used by the UserLogin class to authenticate users?

2. What information is included in the JWT access token generated by the UserLogin method?