Source code for django.contrib.contenttypes.prefetch

from django.db.models import Prefetch
from django.db.models.query import ModelIterable, RawQuerySet


[docs] class GenericPrefetch(Prefetch): def __init__(self, lookup, querysets=None, to_attr=None): for queryset in querysets: if queryset is not None and ( isinstance(queryset, RawQuerySet) or ( hasattr(queryset, "_iterable_class") and not issubclass(queryset._iterable_class, ModelIterable) ) ): raise ValueError( "Prefetch querysets cannot use raw(), values(), and values_list()." ) self.querysets = querysets super().__init__(lookup, to_attr=to_attr) def __getstate__(self): obj_dict = self.__dict__.copy() obj_dict["querysets"] = [] for queryset in self.querysets: if queryset is not None: queryset = queryset._chain() # Prevent the QuerySet from being evaluated queryset._result_cache = [] queryset._prefetch_done = True obj_dict["querysets"].append(queryset) return obj_dict def get_current_querysets(self, level): if self.get_current_prefetch_to(level) == self.prefetch_to: return self.querysets return None