def registration_options(self):
        """Gathers values for common attributes between the
        registration model and this instance.
        """
        registration_options = {}
        rs = self.registration_model()
        for k, v in self.__dict__.items():
            if k not in DEFAULT_BASE_FIELDS + ['_state']:
                try:
                    getattr(rs, k)
                    registration_options.update({k: v})
                except AttributeError:
                    pass
        registration_identifier = registration_options.get(
            'registration_identifier')
        if registration_identifier:
            registration_options['registration_identifier'] = self.to_string(
                registration_identifier)
        return registration_options
Gathers values for common attributes between the
        registration model and this instance.