user_login_needed.py

# decorator for Flask application methods
def user_login_needed(f):
    @wraps(f)
    def decorated_function(*args, **kwargs):
        is_user_logged_in = session['user_logged_in']
        if not is_user_logged_in:
            return redirect(url_for('login'))
        else:
            return f(*args, **kwargs)
    return decorated_function