django-tastypie sample authentication

def is_authenticated(self, request, **kwargs):
        from django.contrib.sessions.models import Session
        if 'sessionid' in request.COOKIES:
            try:
                s = Session.objects.get(pk=request.COOKIES['sessionid'])
            except Exception,e:
                logger.warning("user with sessionid : %s not found" % request.COOKIES['sessionid'])
                return False

            # get the user_id from the session
            if '_auth_user_id' in s.get_decoded():
                # try to find the user associated with the given sessionid
                try:
                    u = User.objects.get(pk=s.get_decoded()['_auth_user_id'])
                    if u is not None:
                        return True
                except Exception,e:
                    return False
            else:
                return False
        else:
            logger.warning("sessionid is missing in the request")
            return False