Flask is a commonly used web framework for Python that enables developers to efficiently create web applications. User authentication and authorization are crucial components of any web application. In this article, I will demonstrate how to create a login page with Flask and incorporate GitHub for authentication.
Setting Up Flask
First, let’s make sure we have Flask installed. If you haven’t done so already, open your terminal and type the following command:
pip install flask
This will install Flask and its dependencies on your system. Once Flask is installed, you can start building your login page.
Creating the Login Page
To create a login page in Flask, we need to define a route and a corresponding HTML template. Create a new file called login.py and add the following code:
from flask import Flask, render_template
app = Flask(__name__)
@app.route('/login')
def login():
return render_template('login.html')
In the code above, we import the necessary modules and create a Flask app instance. We then define a route for /login and a corresponding function login. This function uses the render_template function to render an HTML template called login.html.
Next, let’s create the login.html template. Create a new file called login.html in the same directory as login.py and add the following code:
{% extends 'base.html' %}
{% block content %}
Login
{% endblock %}
In this template, we use the extends keyword to inherit from a base template called base.html. We then define a content block where we add the login form. The form contains fields for the username, password, and a submit button.
Integrating with GitHub
Now that we have our login page, let’s integrate it with GitHub for authentication. To do this, we’ll be using the Flask-Login extension. Open your terminal and type the following command to install Flask-Login:
pip install flask-login
Once Flask-Login is installed, we can update our login.py file to implement the authentication logic. Add the following code to your login.py file:
from flask import Flask, render_template
from flask_login import LoginManager, login_user
app = Flask(__name__)
login_manager = LoginManager(app)
@login_manager.user_loader
def load_user(user_id):
# TODO: Implement user loading logic
return None
@app.route('/login', methods=['GET', 'POST'])
def login():
# TODO: Implement login logic
return render_template('login.html')
In the code above, we import the Flask-Login module and create a login manager instance. We then define a load_user function that will be used to retrieve a user object based on a user id. Lastly, we update the login function to handle both GET and POST requests, as well as importing the render_template function.
To implement the login logic, we need to handle the POST request and authenticate the user. We can use the login_user function provided by Flask-Login to login the user. Add the following code to your login.py file:
from flask import Flask, render_template, redirect, url_for
from flask_login import LoginManager, login_user
app = Flask(__name__)
login_manager = LoginManager(app)
@login_manager.user_loader
def load_user(user_id):
# TODO: Implement user loading logic
return None
@app.route('/login', methods=['GET', 'POST'])
def login():
if request.method == 'POST':
# TODO: Implement authentication logic
user = User(username)
login_user(user)
return redirect(url_for('dashboard'))
return render_template('login.html')
In the code above, we check if the request method is POST. If it is, we assume the user has submitted the login form and proceed with the authentication logic. In this example, we create a user object and use the login_user function to log the user in. After successful authentication, we redirect the user to a dashboard page. If the request method is GET, we simply render the login template as before.
Conclusion
In this article, we explored how to create a login page using Flask and integrate it with GitHub for authentication. We started by setting up Flask and then created the login page itself. We then integrated Flask-Login to handle authentication and implemented the login logic. By following these steps, you now have a fully functional login page that authenticates users using their GitHub credentials. Happy coding!
