mirrors/django
1
0
Fork 0
mirror of https://github.com/django/django.git synced 2025-10-23 21:59:11 +00:00
Code Issues 32 Releases Wiki Activity

[1.11.x] Fixed #27554 -- Fixed prefetch_related() crash when fetching relations in nested Prefetches.

Browse Source 
Backport of c0a2b9508a from master
This commit is contained in:
François Freitag
2017-03-03 18:45:31 -08:00
committed by Tim Graham
parent fec151222e
commit c679ac0449
3 changed files with 46 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
tests/prefetch_related/tests.py
View File

@@ -1391,3 +1391,37 @@ class Ticket25546Tests(TestCase):
self.assertListEqual(book1.first_authors[0].happy_place, [self.author1_address1])
self.assertListEqual(book1.first_authors[1].happy_place, [])
self.assertListEqual(book2.first_authors[0].happy_place, [self.author2_address1])
class ReadPrefetchedObjectsCacheTests(TestCase):
@classmethod
def setUpTestData(cls):
cls.book1 = Book.objects.create(title='Les confessions Volume I')
cls.book2 = Book.objects.create(title='Candide')
cls.author1 = AuthorWithAge.objects.create(name='Rousseau', first_book=cls.book1, age=70)
cls.author2 = AuthorWithAge.objects.create(name='Voltaire', first_book=cls.book2, age=65)
cls.book1.authors.add(cls.author1)
cls.book2.authors.add(cls.author2)
FavoriteAuthors.objects.create(author=cls.author1, likes_author=cls.author2)
def test_retrieves_results_from_prefetched_objects_cache(self):
"""
When intermediary results are prefetched without a destination
attribute, they are saved in the RelatedManager's cache
(_prefetched_objects_cache). prefetch_related() uses this cache
(#27554).
"""
authors = AuthorWithAge.objects.prefetch_related(
Prefetch(
'author',
queryset=Author.objects.prefetch_related(
# Results are saved in the RelatedManager's cache
# (_prefetched_objects_cache) and do not replace the
# RelatedManager on Author instances (favorite_authors)
Prefetch('favorite_authors__first_book'),
),
),
)
with self.assertNumQueries(4):
# AuthorWithAge -> Author -> FavoriteAuthors, Book
self.assertQuerysetEqual(authors, ['<AuthorWithAge: Rousseau>', '<AuthorWithAge: Voltaire>'])