flask-principal

import os from flask import Flask, session, g, redirect, url_for from flask_principal import Principal, Identity, AnonymousIdentity, \ identity_changed, identity_loaded, \ current_identity, \ Need, UserNeed, RoleNeed, Permission # Initialize Flask app app = Flask(__name__) app.secret_key = os.environ.get('FLASK_SECRET_KEY', 'default_secret_key') # Initialize Flask-Principal principals = Principal(app) # Define a permission for 'admin' role admin_permission = Permission(RoleNeed('admin')) @app.before_request def load_identity_from_session(): # Load identity from session or create an anonymous one if 'identity_id' in session: g.identity = Identity(session['identity_id']) # Signal that the identity has loaded identity_changed.send(app, identity=g.identity) else: g.identity = AnonymousIdentity() @identity_loaded.connect_via(app) def on_identity_loaded(sender, identity): # This signal is fired when an identity is loaded (or changed) # Use this to add Needs to the identity based on your application logic if identity.id: # Example: user_id 1 is an admin, others are regular users if identity.id == 1: identity.provides.add(RoleNeed('admin')) identity.provides.add(UserNeed(identity.id)) # All logged-in users get their UserNeed # For anonymous users, no specific Needs are added here by default @app.route('/login/<int:user_id>') def login(user_id): # Simulate a login: set identity in session and emit signal session['identity_id'] = user_id identity_changed.send(app, identity=Identity(user_id)) return f'Logged in as User {user_id}. <a href="{url_for("profile")}">Go to profile</a> <a href="{url_for("admin_dashboard")}">Go to admin dashboard</a>' @app.route('/logout') def logout(): # Simulate a logout: clear session and emit anonymous identity signal if 'identity_id' in session: del session['identity_id'] identity_changed.send(app, identity=AnonymousIdentity()) return 'Logged out. <a href="{url_for("profile")}">Go to profile</a>' @app.route('/') @app.route('/profile') def profile(): if current_identity.is_authenticated(): return f'Hello, User {current_identity.id}! You are authenticated.' \ f' Role: {"Admin" if admin_permission.can() else "User"}.' return 'Hello, Anonymous User! You are not logged in.' @app.route('/admin') @admin_permission.require() # This decorator enforces the 'admin' permission def admin_dashboard(): return f'Welcome to the Admin Dashboard, User {current_identity.id}!' if __name__ == '__main__': # For local testing, ensure a secret key is set if 'FLASK_SECRET_KEY' not in os.environ: print("WARNING: FLASK_SECRET_KEY environment variable not set. Using a default for demonstration.") app.run(debug=True)