How to implement a 'before' hook that can output an alternative response?

Question

Need to do some authentication checks before deciding what content to display. Ideally, I'd like to have a restrictive base handler, that would implement the "before" hook that could show an alternative content, instead of the requested content.

class Restrictive(webapp2.RequestHandler):
    def __init__(self, *args, **kwargs):
        if not self.is_logged_in():
            self.response.write('not logged in')
            self.abort(200)
    def is_logged_in(self):
         return False

But this won't output the response, only headers. What is the proper way of aborting the requested handler and showing alternative content?

Thanks.

Answer 1

I wrote this decorator once.

def authenticated(handler):
    """
        Decorator for checking if there's a user associated with the current session.
        Will also fail if there's no session present.
    """
    def check_login(self, *args, **kwargs):
        if not self.is_logged_in():
           self.response.write('not logged in')
           return self.error(403) 
        else:
           return handler(self, *args, **kwargs)
    return check_login

You can then decorate your methods if they need to be authenticated.

class MyHandler:
    @authenticated
    def get(self):
        pass