Project 7: Missing Routes Protection with Flask-Principal Permissions – Login Session Test

In this tutorial, we will cover how to implement protection with permissions in Flask-Principal by creating missing routes in the project 7. This will help us to ensure that only authorized users can access certain routes in our application.

Step 1: Setting up Flask-Principal
First, we need to install Flask-Principal. You can do this by running the following command in your terminal:

pip install Flask-Principal

Next, we need to import Flask-Principal in our Flask application:

from flask_principal import Principal

And initialize the principal object in our Flask app:

app = Flask(__name__)
principal = Principal(app)

Step 2: Creating Permissions
Now that we have Flask-Principal set up, we need to create permissions for our routes. Permissions in Flask-Principal are defined using the Permission class. Here’s an example of how we can define a permission:

from flask_principal import Permission

admin_permission = Permission('admin')

Step 3: Protecting Routes with Permissions
Now that we have created our permissions, we can protect our routes by checking if the current user has the required permission. Here’s an example of how we can protect a route using Flask-Principal:

from flask import request
from flask_principal import RoleNeed, UserNeed, identity_changed, identity_loaded

@app.route('/admin')
@admin_permission.require(http_exception=403)
def admin_route():
    # Only users with the 'admin' permission can access this route
    return 'Admin Dashboard'

In the above example, we have created an admin_route that is only accessible to users with the ‘admin’ permission. If a user without the required permission tries to access this route, they will receive a 403 Forbidden error.

Step 4: Implementing Login and Logout Functionality
To ensure that the correct permissions are applied to the current user, we need to implement a login and logout functionality. You can create login and logout routes in your Flask application and use the identity_changed and identity_loaded functions to set the current user’s identity.

Here’s an example of how you can implement login and logout routes:

@app.route('/login')
def login():
    # authenticate user
    user = User.query.filter_by(username=request.form['username']).first()

    # Set the current user's identity
    identity_changed.send(app, identity=UserNeed(user.id))

    return 'Logged in successfully'

@app.route('/logout')
def logout():
    # Remove the current user's identity
    identity_changed.send(app, identity=UserNeed('guest'))

    return 'Logged out successfully'

In the above example, we have created login and logout routes that set the current user’s identity after successful authentication and remove the current user’s identity upon logout.

Step 5: Passing Permissions to Templates
To display different content based on the user’s permissions, you can pass the permissions to your templates. Here’s an example of how you can pass the current user’s permissions to a template:

@app.context_processor
def inject_permissions():
    return {'permissions': current_permissions()}

In the above example, we are creating a context processor that injects the current user’s permissions into our templates. You can then use these permissions in your templates to display different content based on the user’s permissions.

That’s it! You have successfully implemented protection with permissions in Flask-Principal by creating missing routes in the project 7. You can now ensure that only authorized users can access certain routes in your Flask application.