Schematics serializer override

        The return values vary to indicate whether or not the
        relationships is loaded with values (list with members),
        loaded but no values (empty list), or never loaded &
        unknown if values exist or not.

def to_primitive(self, value, context=None):
        """ Schematics serializer override

        The return values vary to indicate whether or not the
        relationships is loaded with values (list with members),
        loaded but no values (empty list), or never loaded &
        unknown if values exist or not.
        """

        data = []

        if not value.is_loaded:
            return None

        for model in value.models:
            if context and context.get('rel_ids'):
                data.append(model.rid_value)
            else:
                data.append({'rtype': model.rtype, 'rid': model.rid_value})

        return data