def _build_message(self):
        """
        
        """
        if self.message_type in ['text', 'markdown']:
            data = {
                'msgtype': self.message_type,
                self.message_type: {
                    'content': self.message
                } if self.message_type == 'text' else self.message,
                'at': {
                    'atMobiles': self.at_mobiles,
                    'isAtAll': self.at_all
                }
            }
        else:
            data = {
                'msgtype': self.message_type,
                self.message_type: self.message
            }
        return json.dumps(data)