stores.py 文件源码

def last_updated(self):
        doc = next(self.query(properties=[self.lu_field]).sort(
            [(self.lu_field, pymongo.DESCENDING)]).limit(1), None)
        # Handle when collection has docs but `NoneType` lu_field.
        return (self.lu_func[0](doc[self.lu_field]) if (doc and doc[self.lu_field])
                else datetime.min)