query_utils.py 文件源码

def _get_lookup(self, lookup_name):
        try:
            return self.class_lookups[lookup_name]
        except KeyError:
            # To allow for inheritance, check parent class' class_lookups.
            for parent in inspect.getmro(self.__class__):
                if 'class_lookups' not in parent.__dict__:
                    continue
                if lookup_name in parent.class_lookups:
                    return parent.class_lookups[lookup_name]
        except AttributeError:
            # This class didn't have any class_lookups
            pass
        return None