How to merge Flask login with a Dash application?

Question

I have to design a web-app that provides Flask services and Dash services. For example I would like to create a login in Flask, combined with a Dash application. The problem is that I can't bind the flask login with dash. I would need a method like '@require_login' that filters access to even Dash services. The code is as follows:

app_flask = Flask(__name__)

app_flask.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////login.db'
app_flask.config['SECRET_KEY'] = 'thisissecret'

db = SQLAlchemy(app_flask)
login_manager = LoginManager()
login_manager.init_app(app_flask)

class User(UserMixin, db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(30), unique=True)

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

@app_flask.route('/')
def index():
    user = User.query.filter_by(username='admin').first()
    login_user(user)
    return 'You are now logged in!'

@app_flask.route('/logout')
@login_required
def logout():
    logout_user()
    return 'You are now logged out!'

@app_flask.route('/home')
@login_required
def home():
    return 'The current FLASK user is ' + current_user.username

# TODO how to add login_required for dash? 
app_dash = Dash(server=app_flask, url_base_pathname='/dash/')
app_dash.layout = html.H1('MY DASH APP')


if __name__ == '__main__':
    app_dash.run_server(debug=True)

Answer 1

This line, app_dash = Dash(server=app_flask, url_base_pathname='/dash/'), creates new view_functions in app_flask identified by its url_base_pathname.

You can debug and inspect the value of app_flask.view_functions before and after the creation of app_dash.

Now that we know which view_functions are created by app_dash, we can apply login_required to them manually.

for view_func in app_flask.view_functions:
    if view_func.startswith(app_dash.url_base_pathname):
        app_flask.view_functions[view_func] = login_required(app_flask.view_functions[view_func])

The `app_dash` endpoints will now be protected.