related_descriptors.py 文件源码

def get_prefetch_queryset(self, instances, queryset=None):
        if queryset is None:
            queryset = self.get_queryset()
        queryset._add_hints(instance=instances[0])

        rel_obj_attr = attrgetter(self.related.field.attname)
        instance_attr = lambda obj: obj._get_pk_val()
        instances_dict = {instance_attr(inst): inst for inst in instances}
        query = {'%s__in' % self.related.field.name: instances}
        queryset = queryset.filter(**query)

        # Since we're going to assign directly in the cache,
        # we must manage the reverse relation cache manually.
        rel_obj_cache_name = self.related.field.get_cache_name()
        for rel_obj in queryset:
            instance = instances_dict[rel_obj_attr(rel_obj)]
            setattr(rel_obj, rel_obj_cache_name, instance)
        return queryset, rel_obj_attr, instance_attr, True, self.cache_name