Flask-Login User Authentication Implementation

This code example uses the Flask-Login library to implement user login functionality. It first defines a User class that inherits from UserMixin, then initializes a LoginManager. The user_loader decorator is used to load the user object. The login_with_user function is used to log in a user based on the user ID.

Technology Stack : Flask, Flask-Login

Code Type : Example of using Flask-Login

Code Difficulty : Intermediate

                
                    
from flask_login import LoginManager, UserMixin, login_user, logout_user, login_required, current_user

class User(UserMixin):
    # A simple user class with some basic attributes
    def __init__(self, id):
        self.id = id

# Initialize the login manager
login_manager = LoginManager()
login_manager.init_app(app)

@login_manager.user_loader
def load_user(user_id):
    # This callback is used to reload the user object from the user ID stored in the session
    return User(user_id)

def login_with_user(user_id):
    """
    This function logs in a user with a given user_id using the Flask-Login library.
    """
    user = User(user_id)
    login_user(user)

    return f"User {user_id} logged in successfully."