Schematics validator

        The provided rtype must match that of the
        underlying model.

        :return: str

def validate_rtype(self, value):
        """ Schematics validator

        The provided rtype must match that of the
        underlying model.

        :return: str
        """

        if not value or value != self.rtype:
            msg = self.messages['rtype'].format(self.rtype, value)
            raise ValidationError(msg)
        return value