def insert(self, doc, synced=False):
        doc.id = self.get_next_id()
        doc.synced = synced
        try:
            self.db.docs.insert(doc)
        except Exception as e:
            raise DatabaseException(e)
        return doc
def index(self, request):
        queryset = Condition.objects.select_related('source', 'target_option')
        serializer = ConditionIndexSerializer(queryset, many=True)
        return Response(serializer.data)