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[5.0.x] Fixed #34889 -- Fixed get_prefetch_queryset() fallback in prefetch_one_level().

Thanks Matt Westcott for the report.

Regression in cac94dd8aa.
Backport of 296b75a3c0 from main
This commit is contained in:
Mariusz Felisiak 2023-10-06 20:18:41 +02:00
parent d5b093a2c5
commit 9f8bf7aebe
2 changed files with 46 additions and 5 deletions

View File

@ -2550,6 +2550,9 @@ def prefetch_one_level(instances, prefetcher, lookup, level):
RemovedInDjango60Warning,
stacklevel=2,
)
queryset = None
if querysets := lookup.get_current_querysets(level):
queryset = querysets[0]
(
rel_qs,
rel_obj_attr,
@ -2557,9 +2560,7 @@ def prefetch_one_level(instances, prefetcher, lookup, level):
single,
cache_name,
is_descriptor,
) = prefetcher.get_prefetch_queryset(
instances, lookup.get_current_querysets(level)
)
) = prefetcher.get_prefetch_queryset(instances, queryset)
# We have to handle the possibility that the QuerySet we just got back
# contains some prefetch_related lookups. We don't want to trigger the
# prefetch_related functionality by evaluating the query. Rather, we need

View File

@ -4,10 +4,12 @@ from django.contrib.contenttypes.models import ContentType
from django.core.exceptions import ObjectDoesNotExist
from django.db import NotSupportedError, connection
from django.db.models import Prefetch, QuerySet, prefetch_related_objects
from django.db.models.query import get_prefetcher
from django.db.models.fields.related import ForwardManyToOneDescriptor
from django.db.models.query import get_prefetcher, prefetch_one_level
from django.db.models.sql import Query
from django.test import (
TestCase,
ignore_warnings,
override_settings,
skipIfDBFeature,
skipUnlessDBFeature,
@ -1997,7 +1999,7 @@ class PrefetchLimitTests(TestDataMixin, TestCase):
list(Book.objects.prefetch_related(Prefetch("authors", authors[1:])))
class GetCurrentQuerySetDeprecation(TestCase):
class DeprecationTests(TestCase):
def test_get_current_queryset_warning(self):
msg = (
"Prefetch.get_current_queryset() is deprecated. Use "
@ -2011,3 +2013,41 @@ class GetCurrentQuerySetDeprecation(TestCase):
)
with self.assertWarnsMessage(RemovedInDjango60Warning, msg):
self.assertIsNone(Prefetch("authors").get_current_queryset(1))
@ignore_warnings(category=RemovedInDjango60Warning)
def test_prefetch_one_level_fallback(self):
class NoGetPrefetchQuerySetsDescriptor(ForwardManyToOneDescriptor):
def get_prefetch_queryset(self, instances, queryset=None):
if queryset is None:
return super().get_prefetch_querysets(instances)
return super().get_prefetch_querysets(instances, [queryset])
def __getattribute__(self, name):
if name == "get_prefetch_querysets":
raise AttributeError
return super().__getattribute__(name)
house = House.objects.create()
room = Room.objects.create(house=house)
house.main_room = room
house.save()
# prefetch_one_level() fallbacks to get_prefetch_queryset().
prefetcher = NoGetPrefetchQuerySetsDescriptor(Room._meta.get_field("house"))
obj_list, additional_lookups = prefetch_one_level(
[room],
prefetcher,
Prefetch("house", House.objects.all()),
0,
)
self.assertEqual(obj_list, [house])
self.assertEqual(additional_lookups, [])
obj_list, additional_lookups = prefetch_one_level(
[room],
prefetcher,
Prefetch("house"),
0,
)
self.assertEqual(obj_list, [house])
self.assertEqual(additional_lookups, [])