def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def detail_export(self, request, pk=None):
        serializer = ConditionExportSerializer(self.get_object())
        xml = ConditionRenderer().render([serializer.data])
        return XMLResponse(xml, name=self.get_object().key)