Flask-Login shows 401 instead of redirecting to login view

Question

Using Flask-Login, I want to require login for some views. When I try to access a view that is decorated with @login_required, I get a 401 message instead of the login page. How do I set this up correctly?

from flask_login import LoginManager, login_required, login_user

login_manager = LoginManager()
login_manager.init_app(app)

@login_manager.user_loader
def load_user(user_id):
    return User.get(user_id)

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        # authenticate user from form
        login_user(user)
        return redirect(url_for('index'))

    return render_template('login.html')

@app.route('/protected')
@login_required
def protected():
    return 'Hello, World!'

Answer 1

You haven't told Flask-Login what view to use to show the login form, so it defaults to a generic 401 error. From the docs: "If the login view is not set, it will abort with a 401 error."

login_manager.login_view = 'login'