1854 lines
71 KiB
Python
1854 lines
71 KiB
Python
from unittest import mock
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from django.contrib.contenttypes.models import ContentType
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from django.core.exceptions import ObjectDoesNotExist
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from django.db import connection
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from django.db.models import Prefetch, QuerySet, prefetch_related_objects
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from django.db.models.query import get_prefetcher
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from django.db.models.sql import Query
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from django.test import TestCase, override_settings
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from django.test.utils import CaptureQueriesContext
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from .models import (
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Article,
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Author,
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Author2,
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AuthorAddress,
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AuthorWithAge,
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Bio,
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Book,
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Bookmark,
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BookReview,
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BookWithYear,
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Comment,
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Department,
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Employee,
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FavoriteAuthors,
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House,
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LessonEntry,
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ModelIterableSubclass,
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Person,
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Qualification,
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Reader,
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Room,
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TaggedItem,
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Teacher,
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WordEntry,
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)
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class TestDataMixin:
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@classmethod
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def setUpTestData(cls):
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cls.book1 = Book.objects.create(title="Poems")
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cls.book2 = Book.objects.create(title="Jane Eyre")
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cls.book3 = Book.objects.create(title="Wuthering Heights")
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cls.book4 = Book.objects.create(title="Sense and Sensibility")
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cls.author1 = Author.objects.create(name="Charlotte", first_book=cls.book1)
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cls.author2 = Author.objects.create(name="Anne", first_book=cls.book1)
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cls.author3 = Author.objects.create(name="Emily", first_book=cls.book1)
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cls.author4 = Author.objects.create(name="Jane", first_book=cls.book4)
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cls.book1.authors.add(cls.author1, cls.author2, cls.author3)
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cls.book2.authors.add(cls.author1)
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cls.book3.authors.add(cls.author3)
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cls.book4.authors.add(cls.author4)
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cls.reader1 = Reader.objects.create(name="Amy")
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cls.reader2 = Reader.objects.create(name="Belinda")
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cls.reader1.books_read.add(cls.book1, cls.book4)
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cls.reader2.books_read.add(cls.book2, cls.book4)
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class PrefetchRelatedTests(TestDataMixin, TestCase):
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def assertWhereContains(self, sql, needle):
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where_idx = sql.index("WHERE")
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self.assertEqual(
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sql.count(str(needle), where_idx),
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1,
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msg="WHERE clause doesn't contain %s, actual SQL: %s"
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% (needle, sql[where_idx:]),
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)
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def test_m2m_forward(self):
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with self.assertNumQueries(2):
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lists = [
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list(b.authors.all()) for b in Book.objects.prefetch_related("authors")
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]
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normal_lists = [list(b.authors.all()) for b in Book.objects.all()]
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self.assertEqual(lists, normal_lists)
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def test_m2m_reverse(self):
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with self.assertNumQueries(2):
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lists = [
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list(a.books.all()) for a in Author.objects.prefetch_related("books")
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]
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normal_lists = [list(a.books.all()) for a in Author.objects.all()]
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self.assertEqual(lists, normal_lists)
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def test_foreignkey_forward(self):
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with self.assertNumQueries(2):
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books = [
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a.first_book for a in Author.objects.prefetch_related("first_book")
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]
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normal_books = [a.first_book for a in Author.objects.all()]
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self.assertEqual(books, normal_books)
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def test_foreignkey_reverse(self):
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with self.assertNumQueries(2):
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[
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list(b.first_time_authors.all())
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for b in Book.objects.prefetch_related("first_time_authors")
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]
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self.assertSequenceEqual(self.book2.authors.all(), [self.author1])
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def test_onetoone_reverse_no_match(self):
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# Regression for #17439
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with self.assertNumQueries(2):
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book = Book.objects.prefetch_related("bookwithyear").all()[0]
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with self.assertNumQueries(0):
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with self.assertRaises(BookWithYear.DoesNotExist):
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book.bookwithyear
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def test_onetoone_reverse_with_to_field_pk(self):
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"""
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A model (Bio) with a OneToOneField primary key (author) that references
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a non-pk field (name) on the related model (Author) is prefetchable.
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"""
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Bio.objects.bulk_create(
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[
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Bio(author=self.author1),
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Bio(author=self.author2),
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Bio(author=self.author3),
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]
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)
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authors = Author.objects.filter(
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name__in=[self.author1, self.author2, self.author3],
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).prefetch_related("bio")
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with self.assertNumQueries(2):
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for author in authors:
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self.assertEqual(author.name, author.bio.author.name)
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def test_survives_clone(self):
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with self.assertNumQueries(2):
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[
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list(b.first_time_authors.all())
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for b in Book.objects.prefetch_related("first_time_authors").exclude(
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id=1000
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)
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]
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def test_len(self):
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with self.assertNumQueries(2):
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qs = Book.objects.prefetch_related("first_time_authors")
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len(qs)
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[list(b.first_time_authors.all()) for b in qs]
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def test_bool(self):
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with self.assertNumQueries(2):
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qs = Book.objects.prefetch_related("first_time_authors")
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bool(qs)
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[list(b.first_time_authors.all()) for b in qs]
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def test_count(self):
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with self.assertNumQueries(2):
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qs = Book.objects.prefetch_related("first_time_authors")
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[b.first_time_authors.count() for b in qs]
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def test_exists(self):
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with self.assertNumQueries(2):
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qs = Book.objects.prefetch_related("first_time_authors")
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[b.first_time_authors.exists() for b in qs]
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def test_in_and_prefetch_related(self):
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"""
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Regression test for #20242 - QuerySet "in" didn't work the first time
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when using prefetch_related. This was fixed by the removal of chunked
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reads from QuerySet iteration in
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70679243d1786e03557c28929f9762a119e3ac14.
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"""
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qs = Book.objects.prefetch_related("first_time_authors")
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self.assertIn(qs[0], qs)
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def test_clear(self):
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with self.assertNumQueries(5):
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with_prefetch = Author.objects.prefetch_related("books")
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without_prefetch = with_prefetch.prefetch_related(None)
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[list(a.books.all()) for a in without_prefetch]
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def test_m2m_then_m2m(self):
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"""A m2m can be followed through another m2m."""
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with self.assertNumQueries(3):
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qs = Author.objects.prefetch_related("books__read_by")
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lists = [
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[[str(r) for r in b.read_by.all()] for b in a.books.all()] for a in qs
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]
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self.assertEqual(
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lists,
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[
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[["Amy"], ["Belinda"]], # Charlotte - Poems, Jane Eyre
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[["Amy"]], # Anne - Poems
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[["Amy"], []], # Emily - Poems, Wuthering Heights
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[["Amy", "Belinda"]], # Jane - Sense and Sense
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],
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)
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def test_overriding_prefetch(self):
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with self.assertNumQueries(3):
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qs = Author.objects.prefetch_related("books", "books__read_by")
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lists = [
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[[str(r) for r in b.read_by.all()] for b in a.books.all()] for a in qs
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]
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self.assertEqual(
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lists,
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[
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[["Amy"], ["Belinda"]], # Charlotte - Poems, Jane Eyre
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[["Amy"]], # Anne - Poems
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[["Amy"], []], # Emily - Poems, Wuthering Heights
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[["Amy", "Belinda"]], # Jane - Sense and Sense
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],
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)
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with self.assertNumQueries(3):
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qs = Author.objects.prefetch_related("books__read_by", "books")
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lists = [
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[[str(r) for r in b.read_by.all()] for b in a.books.all()] for a in qs
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]
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self.assertEqual(
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lists,
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[
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[["Amy"], ["Belinda"]], # Charlotte - Poems, Jane Eyre
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[["Amy"]], # Anne - Poems
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[["Amy"], []], # Emily - Poems, Wuthering Heights
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[["Amy", "Belinda"]], # Jane - Sense and Sense
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],
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)
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def test_get(self):
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"""
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Objects retrieved with .get() get the prefetch behavior.
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"""
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# Need a double
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with self.assertNumQueries(3):
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author = Author.objects.prefetch_related("books__read_by").get(
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name="Charlotte"
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)
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lists = [[str(r) for r in b.read_by.all()] for b in author.books.all()]
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self.assertEqual(lists, [["Amy"], ["Belinda"]]) # Poems, Jane Eyre
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def test_foreign_key_then_m2m(self):
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"""
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A m2m relation can be followed after a relation like ForeignKey that
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doesn't have many objects.
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"""
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with self.assertNumQueries(2):
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qs = Author.objects.select_related("first_book").prefetch_related(
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"first_book__read_by"
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)
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lists = [[str(r) for r in a.first_book.read_by.all()] for a in qs]
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self.assertEqual(lists, [["Amy"], ["Amy"], ["Amy"], ["Amy", "Belinda"]])
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def test_reverse_one_to_one_then_m2m(self):
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"""
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A m2m relation can be followed after going through the select_related
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reverse of an o2o.
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"""
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qs = Author.objects.prefetch_related("bio__books").select_related("bio")
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with self.assertNumQueries(1):
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list(qs.all())
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Bio.objects.create(author=self.author1)
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with self.assertNumQueries(2):
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list(qs.all())
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def test_attribute_error(self):
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qs = Reader.objects.all().prefetch_related("books_read__xyz")
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msg = (
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"Cannot find 'xyz' on Book object, 'books_read__xyz' "
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"is an invalid parameter to prefetch_related()"
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)
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with self.assertRaisesMessage(AttributeError, msg) as cm:
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list(qs)
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self.assertIn("prefetch_related", str(cm.exception))
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def test_invalid_final_lookup(self):
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qs = Book.objects.prefetch_related("authors__name")
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msg = (
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"'authors__name' does not resolve to an item that supports "
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"prefetching - this is an invalid parameter to prefetch_related()."
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)
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with self.assertRaisesMessage(ValueError, msg) as cm:
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list(qs)
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self.assertIn("prefetch_related", str(cm.exception))
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self.assertIn("name", str(cm.exception))
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def test_prefetch_eq(self):
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prefetch_1 = Prefetch("authors", queryset=Author.objects.all())
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prefetch_2 = Prefetch("books", queryset=Book.objects.all())
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self.assertEqual(prefetch_1, prefetch_1)
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self.assertEqual(prefetch_1, mock.ANY)
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self.assertNotEqual(prefetch_1, prefetch_2)
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def test_forward_m2m_to_attr_conflict(self):
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msg = "to_attr=authors conflicts with a field on the Book model."
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authors = Author.objects.all()
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with self.assertRaisesMessage(ValueError, msg):
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list(
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Book.objects.prefetch_related(
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Prefetch("authors", queryset=authors, to_attr="authors"),
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)
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)
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# Without the ValueError, an author was deleted due to the implicit
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# save of the relation assignment.
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self.assertEqual(self.book1.authors.count(), 3)
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def test_reverse_m2m_to_attr_conflict(self):
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msg = "to_attr=books conflicts with a field on the Author model."
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poems = Book.objects.filter(title="Poems")
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with self.assertRaisesMessage(ValueError, msg):
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list(
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Author.objects.prefetch_related(
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Prefetch("books", queryset=poems, to_attr="books"),
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)
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)
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# Without the ValueError, a book was deleted due to the implicit
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# save of reverse relation assignment.
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self.assertEqual(self.author1.books.count(), 2)
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def test_m2m_then_reverse_fk_object_ids(self):
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with CaptureQueriesContext(connection) as queries:
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list(Book.objects.prefetch_related("authors__addresses"))
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sql = queries[-1]["sql"]
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self.assertWhereContains(sql, self.author1.name)
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def test_m2m_then_m2m_object_ids(self):
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with CaptureQueriesContext(connection) as queries:
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list(Book.objects.prefetch_related("authors__favorite_authors"))
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sql = queries[-1]["sql"]
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self.assertWhereContains(sql, self.author1.name)
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def test_m2m_then_reverse_one_to_one_object_ids(self):
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with CaptureQueriesContext(connection) as queries:
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list(Book.objects.prefetch_related("authors__authorwithage"))
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sql = queries[-1]["sql"]
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self.assertWhereContains(sql, self.author1.id)
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def test_filter_deferred(self):
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"""
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Related filtering of prefetched querysets is deferred on m2m and
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reverse m2o relations until necessary.
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"""
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add_q = Query.add_q
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for relation in ["authors", "first_time_authors"]:
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with self.subTest(relation=relation):
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with mock.patch.object(
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Query,
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"add_q",
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autospec=True,
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side_effect=lambda self, q: add_q(self, q),
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) as add_q_mock:
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list(Book.objects.prefetch_related(relation))
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self.assertEqual(add_q_mock.call_count, 1)
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def test_named_values_list(self):
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qs = Author.objects.prefetch_related("books")
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self.assertCountEqual(
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[value.name for value in qs.values_list("name", named=True)],
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["Anne", "Charlotte", "Emily", "Jane"],
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)
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class RawQuerySetTests(TestDataMixin, TestCase):
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def test_basic(self):
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with self.assertNumQueries(2):
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books = Book.objects.raw(
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"SELECT * FROM prefetch_related_book WHERE id = %s", (self.book1.id,)
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).prefetch_related("authors")
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book1 = list(books)[0]
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with self.assertNumQueries(0):
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self.assertCountEqual(
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book1.authors.all(), [self.author1, self.author2, self.author3]
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)
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def test_prefetch_before_raw(self):
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with self.assertNumQueries(2):
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books = Book.objects.prefetch_related("authors").raw(
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"SELECT * FROM prefetch_related_book WHERE id = %s", (self.book1.id,)
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)
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book1 = list(books)[0]
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with self.assertNumQueries(0):
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self.assertCountEqual(
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book1.authors.all(), [self.author1, self.author2, self.author3]
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)
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def test_clear(self):
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with self.assertNumQueries(5):
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with_prefetch = Author.objects.raw(
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"SELECT * FROM prefetch_related_author"
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).prefetch_related("books")
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without_prefetch = with_prefetch.prefetch_related(None)
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[list(a.books.all()) for a in without_prefetch]
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class CustomPrefetchTests(TestCase):
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@classmethod
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def traverse_qs(cls, obj_iter, path):
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"""
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Helper method that returns a list containing a list of the objects in the
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obj_iter. Then for each object in the obj_iter, the path will be
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recursively travelled and the found objects are added to the return value.
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"""
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ret_val = []
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if hasattr(obj_iter, "all"):
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obj_iter = obj_iter.all()
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try:
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iter(obj_iter)
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except TypeError:
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obj_iter = [obj_iter]
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for obj in obj_iter:
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rel_objs = []
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for part in path:
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if not part:
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continue
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try:
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related = getattr(obj, part[0])
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except ObjectDoesNotExist:
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continue
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if related is not None:
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rel_objs.extend(cls.traverse_qs(related, [part[1:]]))
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ret_val.append((obj, rel_objs))
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return ret_val
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|
|
@classmethod
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|
def setUpTestData(cls):
|
|
cls.person1 = Person.objects.create(name="Joe")
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cls.person2 = Person.objects.create(name="Mary")
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|
|
# Set main_room for each house before creating the next one for
|
|
# databases where supports_nullable_unique_constraints is False.
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cls.house1 = House.objects.create(
|
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name="House 1", address="123 Main St", owner=cls.person1
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)
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cls.room1_1 = Room.objects.create(name="Dining room", house=cls.house1)
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cls.room1_2 = Room.objects.create(name="Lounge", house=cls.house1)
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cls.room1_3 = Room.objects.create(name="Kitchen", house=cls.house1)
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cls.house1.main_room = cls.room1_1
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cls.house1.save()
|
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cls.person1.houses.add(cls.house1)
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|
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cls.house2 = House.objects.create(
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name="House 2", address="45 Side St", owner=cls.person1
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)
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cls.room2_1 = Room.objects.create(name="Dining room", house=cls.house2)
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cls.room2_2 = Room.objects.create(name="Lounge", house=cls.house2)
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cls.room2_3 = Room.objects.create(name="Kitchen", house=cls.house2)
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cls.house2.main_room = cls.room2_1
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cls.house2.save()
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cls.person1.houses.add(cls.house2)
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|
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cls.house3 = House.objects.create(
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name="House 3", address="6 Downing St", owner=cls.person2
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)
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cls.room3_1 = Room.objects.create(name="Dining room", house=cls.house3)
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cls.room3_2 = Room.objects.create(name="Lounge", house=cls.house3)
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cls.room3_3 = Room.objects.create(name="Kitchen", house=cls.house3)
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cls.house3.main_room = cls.room3_1
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cls.house3.save()
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|
cls.person2.houses.add(cls.house3)
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|
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cls.house4 = House.objects.create(
|
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name="house 4", address="7 Regents St", owner=cls.person2
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)
|
|
cls.room4_1 = Room.objects.create(name="Dining room", house=cls.house4)
|
|
cls.room4_2 = Room.objects.create(name="Lounge", house=cls.house4)
|
|
cls.room4_3 = Room.objects.create(name="Kitchen", house=cls.house4)
|
|
cls.house4.main_room = cls.room4_1
|
|
cls.house4.save()
|
|
cls.person2.houses.add(cls.house4)
|
|
|
|
def test_traverse_qs(self):
|
|
qs = Person.objects.prefetch_related("houses")
|
|
related_objs_normal = ([list(p.houses.all()) for p in qs],)
|
|
related_objs_from_traverse = [
|
|
[inner[0] for inner in o[1]] for o in self.traverse_qs(qs, [["houses"]])
|
|
]
|
|
self.assertEqual(related_objs_normal, (related_objs_from_traverse,))
|
|
|
|
def test_ambiguous(self):
|
|
# Ambiguous: Lookup was already seen with a different queryset.
|
|
msg = (
|
|
"'houses' lookup was already seen with a different queryset. You "
|
|
"may need to adjust the ordering of your lookups."
|
|
)
|
|
# lookup.queryset shouldn't be evaluated.
|
|
with self.assertNumQueries(3):
|
|
with self.assertRaisesMessage(ValueError, msg):
|
|
self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
"houses__rooms",
|
|
Prefetch("houses", queryset=House.objects.all()),
|
|
),
|
|
[["houses", "rooms"]],
|
|
)
|
|
|
|
# Ambiguous: Lookup houses_lst doesn't yet exist when performing
|
|
# houses_lst__rooms.
|
|
msg = (
|
|
"Cannot find 'houses_lst' on Person object, 'houses_lst__rooms' is "
|
|
"an invalid parameter to prefetch_related()"
|
|
)
|
|
with self.assertRaisesMessage(AttributeError, msg):
|
|
self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
"houses_lst__rooms",
|
|
Prefetch(
|
|
"houses", queryset=House.objects.all(), to_attr="houses_lst"
|
|
),
|
|
),
|
|
[["houses", "rooms"]],
|
|
)
|
|
|
|
# Not ambiguous.
|
|
self.traverse_qs(
|
|
Person.objects.prefetch_related("houses__rooms", "houses"),
|
|
[["houses", "rooms"]],
|
|
)
|
|
|
|
self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
"houses__rooms",
|
|
Prefetch("houses", queryset=House.objects.all(), to_attr="houses_lst"),
|
|
),
|
|
[["houses", "rooms"]],
|
|
)
|
|
|
|
def test_m2m(self):
|
|
# Control lookups.
|
|
with self.assertNumQueries(2):
|
|
lst1 = self.traverse_qs(
|
|
Person.objects.prefetch_related("houses"), [["houses"]]
|
|
)
|
|
|
|
# Test lookups.
|
|
with self.assertNumQueries(2):
|
|
lst2 = self.traverse_qs(
|
|
Person.objects.prefetch_related(Prefetch("houses")), [["houses"]]
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
with self.assertNumQueries(2):
|
|
lst2 = self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
Prefetch("houses", to_attr="houses_lst")
|
|
),
|
|
[["houses_lst"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
|
|
def test_reverse_m2m(self):
|
|
# Control lookups.
|
|
with self.assertNumQueries(2):
|
|
lst1 = self.traverse_qs(
|
|
House.objects.prefetch_related("occupants"), [["occupants"]]
|
|
)
|
|
|
|
# Test lookups.
|
|
with self.assertNumQueries(2):
|
|
lst2 = self.traverse_qs(
|
|
House.objects.prefetch_related(Prefetch("occupants")), [["occupants"]]
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
with self.assertNumQueries(2):
|
|
lst2 = self.traverse_qs(
|
|
House.objects.prefetch_related(
|
|
Prefetch("occupants", to_attr="occupants_lst")
|
|
),
|
|
[["occupants_lst"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
|
|
def test_m2m_through_fk(self):
|
|
# Control lookups.
|
|
with self.assertNumQueries(3):
|
|
lst1 = self.traverse_qs(
|
|
Room.objects.prefetch_related("house__occupants"),
|
|
[["house", "occupants"]],
|
|
)
|
|
|
|
# Test lookups.
|
|
with self.assertNumQueries(3):
|
|
lst2 = self.traverse_qs(
|
|
Room.objects.prefetch_related(Prefetch("house__occupants")),
|
|
[["house", "occupants"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
with self.assertNumQueries(3):
|
|
lst2 = self.traverse_qs(
|
|
Room.objects.prefetch_related(
|
|
Prefetch("house__occupants", to_attr="occupants_lst")
|
|
),
|
|
[["house", "occupants_lst"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
|
|
def test_m2m_through_gfk(self):
|
|
TaggedItem.objects.create(tag="houses", content_object=self.house1)
|
|
TaggedItem.objects.create(tag="houses", content_object=self.house2)
|
|
|
|
# Control lookups.
|
|
with self.assertNumQueries(3):
|
|
lst1 = self.traverse_qs(
|
|
TaggedItem.objects.filter(tag="houses").prefetch_related(
|
|
"content_object__rooms"
|
|
),
|
|
[["content_object", "rooms"]],
|
|
)
|
|
|
|
# Test lookups.
|
|
with self.assertNumQueries(3):
|
|
lst2 = self.traverse_qs(
|
|
TaggedItem.objects.prefetch_related(
|
|
Prefetch("content_object"),
|
|
Prefetch("content_object__rooms", to_attr="rooms_lst"),
|
|
),
|
|
[["content_object", "rooms_lst"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
|
|
def test_o2m_through_m2m(self):
|
|
# Control lookups.
|
|
with self.assertNumQueries(3):
|
|
lst1 = self.traverse_qs(
|
|
Person.objects.prefetch_related("houses", "houses__rooms"),
|
|
[["houses", "rooms"]],
|
|
)
|
|
|
|
# Test lookups.
|
|
with self.assertNumQueries(3):
|
|
lst2 = self.traverse_qs(
|
|
Person.objects.prefetch_related(Prefetch("houses"), "houses__rooms"),
|
|
[["houses", "rooms"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
with self.assertNumQueries(3):
|
|
lst2 = self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
Prefetch("houses"), Prefetch("houses__rooms")
|
|
),
|
|
[["houses", "rooms"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
with self.assertNumQueries(3):
|
|
lst2 = self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
Prefetch("houses", to_attr="houses_lst"), "houses_lst__rooms"
|
|
),
|
|
[["houses_lst", "rooms"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
with self.assertNumQueries(3):
|
|
lst2 = self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
Prefetch("houses", to_attr="houses_lst"),
|
|
Prefetch("houses_lst__rooms", to_attr="rooms_lst"),
|
|
),
|
|
[["houses_lst", "rooms_lst"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
|
|
def test_generic_rel(self):
|
|
bookmark = Bookmark.objects.create(url="http://www.djangoproject.com/")
|
|
TaggedItem.objects.create(content_object=bookmark, tag="django")
|
|
TaggedItem.objects.create(
|
|
content_object=bookmark, favorite=bookmark, tag="python"
|
|
)
|
|
|
|
# Control lookups.
|
|
with self.assertNumQueries(4):
|
|
lst1 = self.traverse_qs(
|
|
Bookmark.objects.prefetch_related(
|
|
"tags", "tags__content_object", "favorite_tags"
|
|
),
|
|
[["tags", "content_object"], ["favorite_tags"]],
|
|
)
|
|
|
|
# Test lookups.
|
|
with self.assertNumQueries(4):
|
|
lst2 = self.traverse_qs(
|
|
Bookmark.objects.prefetch_related(
|
|
Prefetch("tags", to_attr="tags_lst"),
|
|
Prefetch("tags_lst__content_object"),
|
|
Prefetch("favorite_tags"),
|
|
),
|
|
[["tags_lst", "content_object"], ["favorite_tags"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
|
|
def test_traverse_single_item_property(self):
|
|
# Control lookups.
|
|
with self.assertNumQueries(5):
|
|
lst1 = self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
"houses__rooms",
|
|
"primary_house__occupants__houses",
|
|
),
|
|
[["primary_house", "occupants", "houses"]],
|
|
)
|
|
|
|
# Test lookups.
|
|
with self.assertNumQueries(5):
|
|
lst2 = self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
"houses__rooms",
|
|
Prefetch("primary_house__occupants", to_attr="occupants_lst"),
|
|
"primary_house__occupants_lst__houses",
|
|
),
|
|
[["primary_house", "occupants_lst", "houses"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
|
|
def test_traverse_multiple_items_property(self):
|
|
# Control lookups.
|
|
with self.assertNumQueries(4):
|
|
lst1 = self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
"houses",
|
|
"all_houses__occupants__houses",
|
|
),
|
|
[["all_houses", "occupants", "houses"]],
|
|
)
|
|
|
|
# Test lookups.
|
|
with self.assertNumQueries(4):
|
|
lst2 = self.traverse_qs(
|
|
Person.objects.prefetch_related(
|
|
"houses",
|
|
Prefetch("all_houses__occupants", to_attr="occupants_lst"),
|
|
"all_houses__occupants_lst__houses",
|
|
),
|
|
[["all_houses", "occupants_lst", "houses"]],
|
|
)
|
|
self.assertEqual(lst1, lst2)
|
|
|
|
def test_custom_qs(self):
|
|
# Test basic.
|
|
with self.assertNumQueries(2):
|
|
lst1 = list(Person.objects.prefetch_related("houses"))
|
|
with self.assertNumQueries(2):
|
|
lst2 = list(
|
|
Person.objects.prefetch_related(
|
|
Prefetch(
|
|
"houses", queryset=House.objects.all(), to_attr="houses_lst"
|
|
)
|
|
)
|
|
)
|
|
self.assertEqual(
|
|
self.traverse_qs(lst1, [["houses"]]),
|
|
self.traverse_qs(lst2, [["houses_lst"]]),
|
|
)
|
|
|
|
# Test queryset filtering.
|
|
with self.assertNumQueries(2):
|
|
lst2 = list(
|
|
Person.objects.prefetch_related(
|
|
Prefetch(
|
|
"houses",
|
|
queryset=House.objects.filter(
|
|
pk__in=[self.house1.pk, self.house3.pk]
|
|
),
|
|
to_attr="houses_lst",
|
|
)
|
|
)
|
|
)
|
|
self.assertEqual(len(lst2[0].houses_lst), 1)
|
|
self.assertEqual(lst2[0].houses_lst[0], self.house1)
|
|
self.assertEqual(len(lst2[1].houses_lst), 1)
|
|
self.assertEqual(lst2[1].houses_lst[0], self.house3)
|
|
|
|
# Test flattened.
|
|
with self.assertNumQueries(3):
|
|
lst1 = list(Person.objects.prefetch_related("houses__rooms"))
|
|
with self.assertNumQueries(3):
|
|
lst2 = list(
|
|
Person.objects.prefetch_related(
|
|
Prefetch(
|
|
"houses__rooms",
|
|
queryset=Room.objects.all(),
|
|
to_attr="rooms_lst",
|
|
)
|
|
)
|
|
)
|
|
self.assertEqual(
|
|
self.traverse_qs(lst1, [["houses", "rooms"]]),
|
|
self.traverse_qs(lst2, [["houses", "rooms_lst"]]),
|
|
)
|
|
|
|
# Test inner select_related.
|
|
with self.assertNumQueries(3):
|
|
lst1 = list(Person.objects.prefetch_related("houses__owner"))
|
|
with self.assertNumQueries(2):
|
|
lst2 = list(
|
|
Person.objects.prefetch_related(
|
|
Prefetch("houses", queryset=House.objects.select_related("owner"))
|
|
)
|
|
)
|
|
self.assertEqual(
|
|
self.traverse_qs(lst1, [["houses", "owner"]]),
|
|
self.traverse_qs(lst2, [["houses", "owner"]]),
|
|
)
|
|
|
|
# Test inner prefetch.
|
|
inner_rooms_qs = Room.objects.filter(pk__in=[self.room1_1.pk, self.room1_2.pk])
|
|
houses_qs_prf = House.objects.prefetch_related(
|
|
Prefetch("rooms", queryset=inner_rooms_qs, to_attr="rooms_lst")
|
|
)
|
|
with self.assertNumQueries(4):
|
|
lst2 = list(
|
|
Person.objects.prefetch_related(
|
|
Prefetch(
|
|
"houses",
|
|
queryset=houses_qs_prf.filter(pk=self.house1.pk),
|
|
to_attr="houses_lst",
|
|
),
|
|
Prefetch("houses_lst__rooms_lst__main_room_of"),
|
|
)
|
|
)
|
|
|
|
self.assertEqual(len(lst2[0].houses_lst[0].rooms_lst), 2)
|
|
self.assertEqual(lst2[0].houses_lst[0].rooms_lst[0], self.room1_1)
|
|
self.assertEqual(lst2[0].houses_lst[0].rooms_lst[1], self.room1_2)
|
|
self.assertEqual(lst2[0].houses_lst[0].rooms_lst[0].main_room_of, self.house1)
|
|
self.assertEqual(len(lst2[1].houses_lst), 0)
|
|
|
|
# Test ForwardManyToOneDescriptor.
|
|
houses = House.objects.select_related("owner")
|
|
with self.assertNumQueries(6):
|
|
rooms = Room.objects.all().prefetch_related("house")
|
|
lst1 = self.traverse_qs(rooms, [["house", "owner"]])
|
|
with self.assertNumQueries(2):
|
|
rooms = Room.objects.all().prefetch_related(
|
|
Prefetch("house", queryset=houses.all())
|
|
)
|
|
lst2 = self.traverse_qs(rooms, [["house", "owner"]])
|
|
self.assertEqual(lst1, lst2)
|
|
with self.assertNumQueries(2):
|
|
houses = House.objects.select_related("owner")
|
|
rooms = Room.objects.all().prefetch_related(
|
|
Prefetch("house", queryset=houses.all(), to_attr="house_attr")
|
|
)
|
|
lst2 = self.traverse_qs(rooms, [["house_attr", "owner"]])
|
|
self.assertEqual(lst1, lst2)
|
|
room = (
|
|
Room.objects.all()
|
|
.prefetch_related(
|
|
Prefetch("house", queryset=houses.filter(address="DoesNotExist"))
|
|
)
|
|
.first()
|
|
)
|
|
with self.assertRaises(ObjectDoesNotExist):
|
|
getattr(room, "house")
|
|
room = (
|
|
Room.objects.all()
|
|
.prefetch_related(
|
|
Prefetch(
|
|
"house",
|
|
queryset=houses.filter(address="DoesNotExist"),
|
|
to_attr="house_attr",
|
|
)
|
|
)
|
|
.first()
|
|
)
|
|
self.assertIsNone(room.house_attr)
|
|
rooms = Room.objects.all().prefetch_related(
|
|
Prefetch("house", queryset=House.objects.only("name"))
|
|
)
|
|
with self.assertNumQueries(2):
|
|
getattr(rooms.first().house, "name")
|
|
with self.assertNumQueries(3):
|
|
getattr(rooms.first().house, "address")
|
|
|
|
# Test ReverseOneToOneDescriptor.
|
|
houses = House.objects.select_related("owner")
|
|
with self.assertNumQueries(6):
|
|
rooms = Room.objects.all().prefetch_related("main_room_of")
|
|
lst1 = self.traverse_qs(rooms, [["main_room_of", "owner"]])
|
|
with self.assertNumQueries(2):
|
|
rooms = Room.objects.all().prefetch_related(
|
|
Prefetch("main_room_of", queryset=houses.all())
|
|
)
|
|
lst2 = self.traverse_qs(rooms, [["main_room_of", "owner"]])
|
|
self.assertEqual(lst1, lst2)
|
|
with self.assertNumQueries(2):
|
|
rooms = list(
|
|
Room.objects.all().prefetch_related(
|
|
Prefetch(
|
|
"main_room_of",
|
|
queryset=houses.all(),
|
|
to_attr="main_room_of_attr",
|
|
)
|
|
)
|
|
)
|
|
lst2 = self.traverse_qs(rooms, [["main_room_of_attr", "owner"]])
|
|
self.assertEqual(lst1, lst2)
|
|
room = (
|
|
Room.objects.filter(main_room_of__isnull=False)
|
|
.prefetch_related(
|
|
Prefetch("main_room_of", queryset=houses.filter(address="DoesNotExist"))
|
|
)
|
|
.first()
|
|
)
|
|
with self.assertRaises(ObjectDoesNotExist):
|
|
getattr(room, "main_room_of")
|
|
room = (
|
|
Room.objects.filter(main_room_of__isnull=False)
|
|
.prefetch_related(
|
|
Prefetch(
|
|
"main_room_of",
|
|
queryset=houses.filter(address="DoesNotExist"),
|
|
to_attr="main_room_of_attr",
|
|
)
|
|
)
|
|
.first()
|
|
)
|
|
self.assertIsNone(room.main_room_of_attr)
|
|
|
|
# The custom queryset filters should be applied to the queryset
|
|
# instance returned by the manager.
|
|
person = Person.objects.prefetch_related(
|
|
Prefetch("houses", queryset=House.objects.filter(name="House 1")),
|
|
).get(pk=self.person1.pk)
|
|
self.assertEqual(
|
|
list(person.houses.all()),
|
|
list(person.houses.all().all()),
|
|
)
|
|
|
|
def test_nested_prefetch_related_are_not_overwritten(self):
|
|
# Regression test for #24873
|
|
houses_2 = House.objects.prefetch_related(Prefetch("rooms"))
|
|
persons = Person.objects.prefetch_related(Prefetch("houses", queryset=houses_2))
|
|
houses = House.objects.prefetch_related(Prefetch("occupants", queryset=persons))
|
|
list(houses) # queryset must be evaluated once to reproduce the bug.
|
|
self.assertEqual(
|
|
houses.all()[0].occupants.all()[0].houses.all()[1].rooms.all()[0],
|
|
self.room2_1,
|
|
)
|
|
|
|
def test_nested_prefetch_related_with_duplicate_prefetcher(self):
|
|
"""
|
|
Nested prefetches whose name clashes with descriptor names
|
|
(Person.houses here) are allowed.
|
|
"""
|
|
occupants = Person.objects.prefetch_related(
|
|
Prefetch("houses", to_attr="some_attr_name"),
|
|
Prefetch("houses", queryset=House.objects.prefetch_related("main_room")),
|
|
)
|
|
houses = House.objects.prefetch_related(
|
|
Prefetch("occupants", queryset=occupants)
|
|
)
|
|
with self.assertNumQueries(5):
|
|
self.traverse_qs(list(houses), [["occupants", "houses", "main_room"]])
|
|
|
|
def test_values_queryset(self):
|
|
msg = "Prefetch querysets cannot use raw(), values(), and values_list()."
|
|
with self.assertRaisesMessage(ValueError, msg):
|
|
Prefetch("houses", House.objects.values("pk"))
|
|
with self.assertRaisesMessage(ValueError, msg):
|
|
Prefetch("houses", House.objects.values_list("pk"))
|
|
# That error doesn't affect managers with custom ModelIterable subclasses
|
|
self.assertIs(
|
|
Teacher.objects_custom.all()._iterable_class, ModelIterableSubclass
|
|
)
|
|
Prefetch("teachers", Teacher.objects_custom.all())
|
|
|
|
def test_raw_queryset(self):
|
|
msg = "Prefetch querysets cannot use raw(), values(), and values_list()."
|
|
with self.assertRaisesMessage(ValueError, msg):
|
|
Prefetch("houses", House.objects.raw("select pk from house"))
|
|
|
|
def test_to_attr_doesnt_cache_through_attr_as_list(self):
|
|
house = House.objects.prefetch_related(
|
|
Prefetch("rooms", queryset=Room.objects.all(), to_attr="to_rooms"),
|
|
).get(pk=self.house3.pk)
|
|
self.assertIsInstance(house.rooms.all(), QuerySet)
|
|
|
|
def test_to_attr_cached_property(self):
|
|
persons = Person.objects.prefetch_related(
|
|
Prefetch("houses", House.objects.all(), to_attr="cached_all_houses"),
|
|
)
|
|
for person in persons:
|
|
# To bypass caching at the related descriptor level, don't use
|
|
# person.houses.all() here.
|
|
all_houses = list(House.objects.filter(occupants=person))
|
|
with self.assertNumQueries(0):
|
|
self.assertEqual(person.cached_all_houses, all_houses)
|
|
|
|
def test_filter_deferred(self):
|
|
"""
|
|
Related filtering of prefetched querysets is deferred until necessary.
|
|
"""
|
|
add_q = Query.add_q
|
|
with mock.patch.object(
|
|
Query,
|
|
"add_q",
|
|
autospec=True,
|
|
side_effect=lambda self, q: add_q(self, q),
|
|
) as add_q_mock:
|
|
list(
|
|
House.objects.prefetch_related(
|
|
Prefetch("occupants", queryset=Person.objects.all())
|
|
)
|
|
)
|
|
self.assertEqual(add_q_mock.call_count, 1)
|
|
|
|
|
|
class DefaultManagerTests(TestCase):
|
|
@classmethod
|
|
def setUpTestData(cls):
|
|
cls.qual1 = Qualification.objects.create(name="BA")
|
|
cls.qual2 = Qualification.objects.create(name="BSci")
|
|
cls.qual3 = Qualification.objects.create(name="MA")
|
|
cls.qual4 = Qualification.objects.create(name="PhD")
|
|
|
|
cls.teacher1 = Teacher.objects.create(name="Mr Cleese")
|
|
cls.teacher2 = Teacher.objects.create(name="Mr Idle")
|
|
cls.teacher3 = Teacher.objects.create(name="Mr Chapman")
|
|
cls.teacher1.qualifications.add(cls.qual1, cls.qual2, cls.qual3, cls.qual4)
|
|
cls.teacher2.qualifications.add(cls.qual1)
|
|
cls.teacher3.qualifications.add(cls.qual2)
|
|
|
|
cls.dept1 = Department.objects.create(name="English")
|
|
cls.dept2 = Department.objects.create(name="Physics")
|
|
cls.dept1.teachers.add(cls.teacher1, cls.teacher2)
|
|
cls.dept2.teachers.add(cls.teacher1, cls.teacher3)
|
|
|
|
def test_m2m_then_m2m(self):
|
|
with self.assertNumQueries(3):
|
|
# When we prefetch the teachers, and force the query, we don't want
|
|
# the default manager on teachers to immediately get all the related
|
|
# qualifications, since this will do one query per teacher.
|
|
qs = Department.objects.prefetch_related("teachers")
|
|
depts = "".join(
|
|
"%s department: %s\n"
|
|
% (dept.name, ", ".join(str(t) for t in dept.teachers.all()))
|
|
for dept in qs
|
|
)
|
|
|
|
self.assertEqual(
|
|
depts,
|
|
"English department: Mr Cleese (BA, BSci, MA, PhD), Mr Idle (BA)\n"
|
|
"Physics department: Mr Cleese (BA, BSci, MA, PhD), Mr Chapman "
|
|
"(BSci)\n",
|
|
)
|
|
|
|
|
|
class GenericRelationTests(TestCase):
|
|
@classmethod
|
|
def setUpTestData(cls):
|
|
book1 = Book.objects.create(title="Winnie the Pooh")
|
|
book2 = Book.objects.create(title="Do you like green eggs and spam?")
|
|
book3 = Book.objects.create(title="Three Men In A Boat")
|
|
|
|
reader1 = Reader.objects.create(name="me")
|
|
reader2 = Reader.objects.create(name="you")
|
|
reader3 = Reader.objects.create(name="someone")
|
|
|
|
book1.read_by.add(reader1, reader2)
|
|
book2.read_by.add(reader2)
|
|
book3.read_by.add(reader3)
|
|
|
|
cls.book1, cls.book2, cls.book3 = book1, book2, book3
|
|
cls.reader1, cls.reader2, cls.reader3 = reader1, reader2, reader3
|
|
|
|
def test_prefetch_GFK(self):
|
|
TaggedItem.objects.create(tag="awesome", content_object=self.book1)
|
|
TaggedItem.objects.create(tag="great", content_object=self.reader1)
|
|
TaggedItem.objects.create(tag="outstanding", content_object=self.book2)
|
|
TaggedItem.objects.create(tag="amazing", content_object=self.reader3)
|
|
|
|
# 1 for TaggedItem table, 1 for Book table, 1 for Reader table
|
|
with self.assertNumQueries(3):
|
|
qs = TaggedItem.objects.prefetch_related("content_object")
|
|
list(qs)
|
|
|
|
def test_prefetch_GFK_nonint_pk(self):
|
|
Comment.objects.create(comment="awesome", content_object=self.book1)
|
|
|
|
# 1 for Comment table, 1 for Book table
|
|
with self.assertNumQueries(2):
|
|
qs = Comment.objects.prefetch_related("content_object")
|
|
[c.content_object for c in qs]
|
|
|
|
def test_prefetch_GFK_uuid_pk(self):
|
|
article = Article.objects.create(name="Django")
|
|
Comment.objects.create(comment="awesome", content_object_uuid=article)
|
|
qs = Comment.objects.prefetch_related("content_object_uuid")
|
|
self.assertEqual([c.content_object_uuid for c in qs], [article])
|
|
|
|
def test_prefetch_GFK_fk_pk(self):
|
|
book = Book.objects.create(title="Poems")
|
|
book_with_year = BookWithYear.objects.create(book=book, published_year=2019)
|
|
Comment.objects.create(comment="awesome", content_object=book_with_year)
|
|
qs = Comment.objects.prefetch_related("content_object")
|
|
self.assertEqual([c.content_object for c in qs], [book_with_year])
|
|
|
|
def test_traverse_GFK(self):
|
|
"""
|
|
A 'content_object' can be traversed with prefetch_related() and
|
|
get to related objects on the other side (assuming it is suitably
|
|
filtered)
|
|
"""
|
|
TaggedItem.objects.create(tag="awesome", content_object=self.book1)
|
|
TaggedItem.objects.create(tag="awesome", content_object=self.book2)
|
|
TaggedItem.objects.create(tag="awesome", content_object=self.book3)
|
|
TaggedItem.objects.create(tag="awesome", content_object=self.reader1)
|
|
TaggedItem.objects.create(tag="awesome", content_object=self.reader2)
|
|
|
|
ct = ContentType.objects.get_for_model(Book)
|
|
|
|
# We get 3 queries - 1 for main query, 1 for content_objects since they
|
|
# all use the same table, and 1 for the 'read_by' relation.
|
|
with self.assertNumQueries(3):
|
|
# If we limit to books, we know that they will have 'read_by'
|
|
# attributes, so the following makes sense:
|
|
qs = TaggedItem.objects.filter(
|
|
content_type=ct, tag="awesome"
|
|
).prefetch_related("content_object__read_by")
|
|
readers_of_awesome_books = {
|
|
r.name for tag in qs for r in tag.content_object.read_by.all()
|
|
}
|
|
self.assertEqual(readers_of_awesome_books, {"me", "you", "someone"})
|
|
|
|
def test_nullable_GFK(self):
|
|
TaggedItem.objects.create(
|
|
tag="awesome", content_object=self.book1, created_by=self.reader1
|
|
)
|
|
TaggedItem.objects.create(tag="great", content_object=self.book2)
|
|
TaggedItem.objects.create(tag="rubbish", content_object=self.book3)
|
|
|
|
with self.assertNumQueries(2):
|
|
result = [
|
|
t.created_by for t in TaggedItem.objects.prefetch_related("created_by")
|
|
]
|
|
|
|
self.assertEqual(result, [t.created_by for t in TaggedItem.objects.all()])
|
|
|
|
def test_generic_relation(self):
|
|
bookmark = Bookmark.objects.create(url="http://www.djangoproject.com/")
|
|
TaggedItem.objects.create(content_object=bookmark, tag="django")
|
|
TaggedItem.objects.create(content_object=bookmark, tag="python")
|
|
|
|
with self.assertNumQueries(2):
|
|
tags = [
|
|
t.tag
|
|
for b in Bookmark.objects.prefetch_related("tags")
|
|
for t in b.tags.all()
|
|
]
|
|
self.assertEqual(sorted(tags), ["django", "python"])
|
|
|
|
def test_charfield_GFK(self):
|
|
b = Bookmark.objects.create(url="http://www.djangoproject.com/")
|
|
TaggedItem.objects.create(content_object=b, tag="django")
|
|
TaggedItem.objects.create(content_object=b, favorite=b, tag="python")
|
|
|
|
with self.assertNumQueries(3):
|
|
bookmark = Bookmark.objects.filter(pk=b.pk).prefetch_related(
|
|
"tags", "favorite_tags"
|
|
)[0]
|
|
self.assertEqual(
|
|
sorted(i.tag for i in bookmark.tags.all()), ["django", "python"]
|
|
)
|
|
self.assertEqual([i.tag for i in bookmark.favorite_tags.all()], ["python"])
|
|
|
|
def test_custom_queryset(self):
|
|
bookmark = Bookmark.objects.create(url="http://www.djangoproject.com/")
|
|
django_tag = TaggedItem.objects.create(content_object=bookmark, tag="django")
|
|
TaggedItem.objects.create(content_object=bookmark, tag="python")
|
|
|
|
with self.assertNumQueries(2):
|
|
bookmark = Bookmark.objects.prefetch_related(
|
|
Prefetch("tags", TaggedItem.objects.filter(tag="django")),
|
|
).get()
|
|
|
|
with self.assertNumQueries(0):
|
|
self.assertEqual(list(bookmark.tags.all()), [django_tag])
|
|
|
|
# The custom queryset filters should be applied to the queryset
|
|
# instance returned by the manager.
|
|
self.assertEqual(list(bookmark.tags.all()), list(bookmark.tags.all().all()))
|
|
|
|
def test_deleted_GFK(self):
|
|
TaggedItem.objects.create(tag="awesome", content_object=self.book1)
|
|
TaggedItem.objects.create(tag="awesome", content_object=self.book2)
|
|
ct = ContentType.objects.get_for_model(Book)
|
|
|
|
book1_pk = self.book1.pk
|
|
self.book1.delete()
|
|
|
|
with self.assertNumQueries(2):
|
|
qs = TaggedItem.objects.filter(tag="awesome").prefetch_related(
|
|
"content_object"
|
|
)
|
|
result = [
|
|
(tag.object_id, tag.content_type_id, tag.content_object) for tag in qs
|
|
]
|
|
self.assertEqual(
|
|
result,
|
|
[
|
|
(book1_pk, ct.pk, None),
|
|
(self.book2.pk, ct.pk, self.book2),
|
|
],
|
|
)
|
|
|
|
|
|
class MultiTableInheritanceTest(TestCase):
|
|
@classmethod
|
|
def setUpTestData(cls):
|
|
cls.book1 = BookWithYear.objects.create(title="Poems", published_year=2010)
|
|
cls.book2 = BookWithYear.objects.create(title="More poems", published_year=2011)
|
|
cls.author1 = AuthorWithAge.objects.create(
|
|
name="Jane", first_book=cls.book1, age=50
|
|
)
|
|
cls.author2 = AuthorWithAge.objects.create(
|
|
name="Tom", first_book=cls.book1, age=49
|
|
)
|
|
cls.author3 = AuthorWithAge.objects.create(
|
|
name="Robert", first_book=cls.book2, age=48
|
|
)
|
|
cls.author_address = AuthorAddress.objects.create(
|
|
author=cls.author1, address="SomeStreet 1"
|
|
)
|
|
cls.book2.aged_authors.add(cls.author2, cls.author3)
|
|
cls.br1 = BookReview.objects.create(book=cls.book1, notes="review book1")
|
|
cls.br2 = BookReview.objects.create(book=cls.book2, notes="review book2")
|
|
|
|
def test_foreignkey(self):
|
|
with self.assertNumQueries(2):
|
|
qs = AuthorWithAge.objects.prefetch_related("addresses")
|
|
addresses = [
|
|
[str(address) for address in obj.addresses.all()] for obj in qs
|
|
]
|
|
self.assertEqual(addresses, [[str(self.author_address)], [], []])
|
|
|
|
def test_foreignkey_to_inherited(self):
|
|
with self.assertNumQueries(2):
|
|
qs = BookReview.objects.prefetch_related("book")
|
|
titles = [obj.book.title for obj in qs]
|
|
self.assertEqual(titles, ["Poems", "More poems"])
|
|
|
|
def test_m2m_to_inheriting_model(self):
|
|
qs = AuthorWithAge.objects.prefetch_related("books_with_year")
|
|
with self.assertNumQueries(2):
|
|
lst = [
|
|
[str(book) for book in author.books_with_year.all()] for author in qs
|
|
]
|
|
qs = AuthorWithAge.objects.all()
|
|
lst2 = [[str(book) for book in author.books_with_year.all()] for author in qs]
|
|
self.assertEqual(lst, lst2)
|
|
|
|
qs = BookWithYear.objects.prefetch_related("aged_authors")
|
|
with self.assertNumQueries(2):
|
|
lst = [[str(author) for author in book.aged_authors.all()] for book in qs]
|
|
qs = BookWithYear.objects.all()
|
|
lst2 = [[str(author) for author in book.aged_authors.all()] for book in qs]
|
|
self.assertEqual(lst, lst2)
|
|
|
|
def test_parent_link_prefetch(self):
|
|
with self.assertNumQueries(2):
|
|
[a.author for a in AuthorWithAge.objects.prefetch_related("author")]
|
|
|
|
@override_settings(DEBUG=True)
|
|
def test_child_link_prefetch(self):
|
|
with self.assertNumQueries(2):
|
|
authors = [
|
|
a.authorwithage
|
|
for a in Author.objects.prefetch_related("authorwithage")
|
|
]
|
|
|
|
# Regression for #18090: the prefetching query must include an IN clause.
|
|
# Note that on Oracle the table name is upper case in the generated SQL,
|
|
# thus the .lower() call.
|
|
self.assertIn("authorwithage", connection.queries[-1]["sql"].lower())
|
|
self.assertIn(" IN ", connection.queries[-1]["sql"])
|
|
|
|
self.assertEqual(authors, [a.authorwithage for a in Author.objects.all()])
|
|
|
|
|
|
class ForeignKeyToFieldTest(TestCase):
|
|
@classmethod
|
|
def setUpTestData(cls):
|
|
cls.book = Book.objects.create(title="Poems")
|
|
cls.author1 = Author.objects.create(name="Jane", first_book=cls.book)
|
|
cls.author2 = Author.objects.create(name="Tom", first_book=cls.book)
|
|
cls.author3 = Author.objects.create(name="Robert", first_book=cls.book)
|
|
cls.author_address = AuthorAddress.objects.create(
|
|
author=cls.author1, address="SomeStreet 1"
|
|
)
|
|
FavoriteAuthors.objects.create(author=cls.author1, likes_author=cls.author2)
|
|
FavoriteAuthors.objects.create(author=cls.author2, likes_author=cls.author3)
|
|
FavoriteAuthors.objects.create(author=cls.author3, likes_author=cls.author1)
|
|
|
|
def test_foreignkey(self):
|
|
with self.assertNumQueries(2):
|
|
qs = Author.objects.prefetch_related("addresses")
|
|
addresses = [
|
|
[str(address) for address in obj.addresses.all()] for obj in qs
|
|
]
|
|
self.assertEqual(addresses, [[str(self.author_address)], [], []])
|
|
|
|
def test_m2m(self):
|
|
with self.assertNumQueries(3):
|
|
qs = Author.objects.all().prefetch_related("favorite_authors", "favors_me")
|
|
favorites = [
|
|
(
|
|
[str(i_like) for i_like in author.favorite_authors.all()],
|
|
[str(likes_me) for likes_me in author.favors_me.all()],
|
|
)
|
|
for author in qs
|
|
]
|
|
self.assertEqual(
|
|
favorites,
|
|
[
|
|
([str(self.author2)], [str(self.author3)]),
|
|
([str(self.author3)], [str(self.author1)]),
|
|
([str(self.author1)], [str(self.author2)]),
|
|
],
|
|
)
|
|
|
|
|
|
class LookupOrderingTest(TestCase):
|
|
"""
|
|
Test cases that demonstrate that ordering of lookups is important, and
|
|
ensure it is preserved.
|
|
"""
|
|
|
|
@classmethod
|
|
def setUpTestData(cls):
|
|
person1 = Person.objects.create(name="Joe")
|
|
person2 = Person.objects.create(name="Mary")
|
|
|
|
# Set main_room for each house before creating the next one for
|
|
# databases where supports_nullable_unique_constraints is False.
|
|
house1 = House.objects.create(address="123 Main St")
|
|
room1_1 = Room.objects.create(name="Dining room", house=house1)
|
|
Room.objects.create(name="Lounge", house=house1)
|
|
Room.objects.create(name="Kitchen", house=house1)
|
|
house1.main_room = room1_1
|
|
house1.save()
|
|
person1.houses.add(house1)
|
|
|
|
house2 = House.objects.create(address="45 Side St")
|
|
room2_1 = Room.objects.create(name="Dining room", house=house2)
|
|
Room.objects.create(name="Lounge", house=house2)
|
|
house2.main_room = room2_1
|
|
house2.save()
|
|
person1.houses.add(house2)
|
|
|
|
house3 = House.objects.create(address="6 Downing St")
|
|
room3_1 = Room.objects.create(name="Dining room", house=house3)
|
|
Room.objects.create(name="Lounge", house=house3)
|
|
Room.objects.create(name="Kitchen", house=house3)
|
|
house3.main_room = room3_1
|
|
house3.save()
|
|
person2.houses.add(house3)
|
|
|
|
house4 = House.objects.create(address="7 Regents St")
|
|
room4_1 = Room.objects.create(name="Dining room", house=house4)
|
|
Room.objects.create(name="Lounge", house=house4)
|
|
house4.main_room = room4_1
|
|
house4.save()
|
|
person2.houses.add(house4)
|
|
|
|
def test_order(self):
|
|
with self.assertNumQueries(4):
|
|
# The following two queries must be done in the same order as written,
|
|
# otherwise 'primary_house' will cause non-prefetched lookups
|
|
qs = Person.objects.prefetch_related(
|
|
"houses__rooms", "primary_house__occupants"
|
|
)
|
|
[list(p.primary_house.occupants.all()) for p in qs]
|
|
|
|
|
|
class NullableTest(TestCase):
|
|
@classmethod
|
|
def setUpTestData(cls):
|
|
boss = Employee.objects.create(name="Peter")
|
|
Employee.objects.create(name="Joe", boss=boss)
|
|
Employee.objects.create(name="Angela", boss=boss)
|
|
|
|
def test_traverse_nullable(self):
|
|
# Because we use select_related() for 'boss', it doesn't need to be
|
|
# prefetched, but we can still traverse it although it contains some nulls
|
|
with self.assertNumQueries(2):
|
|
qs = Employee.objects.select_related("boss").prefetch_related("boss__serfs")
|
|
co_serfs = [
|
|
list(e.boss.serfs.all()) if e.boss is not None else [] for e in qs
|
|
]
|
|
|
|
qs2 = Employee.objects.select_related("boss")
|
|
co_serfs2 = [
|
|
list(e.boss.serfs.all()) if e.boss is not None else [] for e in qs2
|
|
]
|
|
|
|
self.assertEqual(co_serfs, co_serfs2)
|
|
|
|
def test_prefetch_nullable(self):
|
|
# One for main employee, one for boss, one for serfs
|
|
with self.assertNumQueries(3):
|
|
qs = Employee.objects.prefetch_related("boss__serfs")
|
|
co_serfs = [
|
|
list(e.boss.serfs.all()) if e.boss is not None else [] for e in qs
|
|
]
|
|
|
|
qs2 = Employee.objects.all()
|
|
co_serfs2 = [
|
|
list(e.boss.serfs.all()) if e.boss is not None else [] for e in qs2
|
|
]
|
|
|
|
self.assertEqual(co_serfs, co_serfs2)
|
|
|
|
def test_in_bulk(self):
|
|
"""
|
|
In-bulk does correctly prefetch objects by not using .iterator()
|
|
directly.
|
|
"""
|
|
boss1 = Employee.objects.create(name="Peter")
|
|
boss2 = Employee.objects.create(name="Jack")
|
|
with self.assertNumQueries(2):
|
|
# Prefetch is done and it does not cause any errors.
|
|
bulk = Employee.objects.prefetch_related("serfs").in_bulk(
|
|
[boss1.pk, boss2.pk]
|
|
)
|
|
for b in bulk.values():
|
|
list(b.serfs.all())
|
|
|
|
|
|
class MultiDbTests(TestCase):
|
|
databases = {"default", "other"}
|
|
|
|
def test_using_is_honored_m2m(self):
|
|
B = Book.objects.using("other")
|
|
A = Author.objects.using("other")
|
|
book1 = B.create(title="Poems")
|
|
book2 = B.create(title="Jane Eyre")
|
|
book3 = B.create(title="Wuthering Heights")
|
|
book4 = B.create(title="Sense and Sensibility")
|
|
|
|
author1 = A.create(name="Charlotte", first_book=book1)
|
|
author2 = A.create(name="Anne", first_book=book1)
|
|
author3 = A.create(name="Emily", first_book=book1)
|
|
author4 = A.create(name="Jane", first_book=book4)
|
|
|
|
book1.authors.add(author1, author2, author3)
|
|
book2.authors.add(author1)
|
|
book3.authors.add(author3)
|
|
book4.authors.add(author4)
|
|
|
|
# Forward
|
|
qs1 = B.prefetch_related("authors")
|
|
with self.assertNumQueries(2, using="other"):
|
|
books = "".join(
|
|
"%s (%s)\n"
|
|
% (book.title, ", ".join(a.name for a in book.authors.all()))
|
|
for book in qs1
|
|
)
|
|
self.assertEqual(
|
|
books,
|
|
"Poems (Charlotte, Anne, Emily)\n"
|
|
"Jane Eyre (Charlotte)\n"
|
|
"Wuthering Heights (Emily)\n"
|
|
"Sense and Sensibility (Jane)\n",
|
|
)
|
|
|
|
# Reverse
|
|
qs2 = A.prefetch_related("books")
|
|
with self.assertNumQueries(2, using="other"):
|
|
authors = "".join(
|
|
"%s: %s\n"
|
|
% (author.name, ", ".join(b.title for b in author.books.all()))
|
|
for author in qs2
|
|
)
|
|
self.assertEqual(
|
|
authors,
|
|
"Charlotte: Poems, Jane Eyre\n"
|
|
"Anne: Poems\n"
|
|
"Emily: Poems, Wuthering Heights\n"
|
|
"Jane: Sense and Sensibility\n",
|
|
)
|
|
|
|
def test_using_is_honored_fkey(self):
|
|
B = Book.objects.using("other")
|
|
A = Author.objects.using("other")
|
|
book1 = B.create(title="Poems")
|
|
book2 = B.create(title="Sense and Sensibility")
|
|
|
|
A.create(name="Charlotte Bronte", first_book=book1)
|
|
A.create(name="Jane Austen", first_book=book2)
|
|
|
|
# Forward
|
|
with self.assertNumQueries(2, using="other"):
|
|
books = ", ".join(
|
|
a.first_book.title for a in A.prefetch_related("first_book")
|
|
)
|
|
self.assertEqual("Poems, Sense and Sensibility", books)
|
|
|
|
# Reverse
|
|
with self.assertNumQueries(2, using="other"):
|
|
books = "".join(
|
|
"%s (%s)\n"
|
|
% (b.title, ", ".join(a.name for a in b.first_time_authors.all()))
|
|
for b in B.prefetch_related("first_time_authors")
|
|
)
|
|
self.assertEqual(
|
|
books,
|
|
"Poems (Charlotte Bronte)\nSense and Sensibility (Jane Austen)\n",
|
|
)
|
|
|
|
def test_using_is_honored_inheritance(self):
|
|
B = BookWithYear.objects.using("other")
|
|
A = AuthorWithAge.objects.using("other")
|
|
book1 = B.create(title="Poems", published_year=2010)
|
|
B.create(title="More poems", published_year=2011)
|
|
A.create(name="Jane", first_book=book1, age=50)
|
|
A.create(name="Tom", first_book=book1, age=49)
|
|
|
|
# parent link
|
|
with self.assertNumQueries(2, using="other"):
|
|
authors = ", ".join(a.author.name for a in A.prefetch_related("author"))
|
|
|
|
self.assertEqual(authors, "Jane, Tom")
|
|
|
|
# child link
|
|
with self.assertNumQueries(2, using="other"):
|
|
ages = ", ".join(
|
|
str(a.authorwithage.age) for a in A.prefetch_related("authorwithage")
|
|
)
|
|
|
|
self.assertEqual(ages, "50, 49")
|
|
|
|
def test_using_is_honored_custom_qs(self):
|
|
B = Book.objects.using("other")
|
|
A = Author.objects.using("other")
|
|
book1 = B.create(title="Poems")
|
|
book2 = B.create(title="Sense and Sensibility")
|
|
|
|
A.create(name="Charlotte Bronte", first_book=book1)
|
|
A.create(name="Jane Austen", first_book=book2)
|
|
|
|
# Implicit hinting
|
|
with self.assertNumQueries(2, using="other"):
|
|
prefetch = Prefetch("first_time_authors", queryset=Author.objects.all())
|
|
books = "".join(
|
|
"%s (%s)\n"
|
|
% (b.title, ", ".join(a.name for a in b.first_time_authors.all()))
|
|
for b in B.prefetch_related(prefetch)
|
|
)
|
|
self.assertEqual(
|
|
books,
|
|
"Poems (Charlotte Bronte)\nSense and Sensibility (Jane Austen)\n",
|
|
)
|
|
# Explicit using on the same db.
|
|
with self.assertNumQueries(2, using="other"):
|
|
prefetch = Prefetch(
|
|
"first_time_authors", queryset=Author.objects.using("other")
|
|
)
|
|
books = "".join(
|
|
"%s (%s)\n"
|
|
% (b.title, ", ".join(a.name for a in b.first_time_authors.all()))
|
|
for b in B.prefetch_related(prefetch)
|
|
)
|
|
self.assertEqual(
|
|
books,
|
|
"Poems (Charlotte Bronte)\nSense and Sensibility (Jane Austen)\n",
|
|
)
|
|
|
|
# Explicit using on a different db.
|
|
with self.assertNumQueries(1, using="default"), self.assertNumQueries(
|
|
1, using="other"
|
|
):
|
|
prefetch = Prefetch(
|
|
"first_time_authors", queryset=Author.objects.using("default")
|
|
)
|
|
books = "".join(
|
|
"%s (%s)\n"
|
|
% (b.title, ", ".join(a.name for a in b.first_time_authors.all()))
|
|
for b in B.prefetch_related(prefetch)
|
|
)
|
|
self.assertEqual(
|
|
books,
|
|
"Poems ()\nSense and Sensibility ()\n",
|
|
)
|
|
|
|
|
|
class Ticket19607Tests(TestCase):
|
|
@classmethod
|
|
def setUpTestData(cls):
|
|
LessonEntry.objects.bulk_create(
|
|
LessonEntry(id=id_, name1=name1, name2=name2)
|
|
for id_, name1, name2 in [
|
|
(1, "einfach", "simple"),
|
|
(2, "schwierig", "difficult"),
|
|
]
|
|
)
|
|
WordEntry.objects.bulk_create(
|
|
WordEntry(id=id_, lesson_entry_id=lesson_entry_id, name=name)
|
|
for id_, lesson_entry_id, name in [
|
|
(1, 1, "einfach"),
|
|
(2, 1, "simple"),
|
|
(3, 2, "schwierig"),
|
|
(4, 2, "difficult"),
|
|
]
|
|
)
|
|
|
|
def test_bug(self):
|
|
list(
|
|
WordEntry.objects.prefetch_related(
|
|
"lesson_entry", "lesson_entry__wordentry_set"
|
|
)
|
|
)
|
|
|
|
|
|
class Ticket21410Tests(TestCase):
|
|
@classmethod
|
|
def setUpTestData(cls):
|
|
book1 = Book.objects.create(title="Poems")
|
|
book2 = Book.objects.create(title="Jane Eyre")
|
|
book3 = Book.objects.create(title="Wuthering Heights")
|
|
book4 = Book.objects.create(title="Sense and Sensibility")
|
|
|
|
author1 = Author2.objects.create(name="Charlotte", first_book=book1)
|
|
author2 = Author2.objects.create(name="Anne", first_book=book1)
|
|
author3 = Author2.objects.create(name="Emily", first_book=book1)
|
|
author4 = Author2.objects.create(name="Jane", first_book=book4)
|
|
|
|
author1.favorite_books.add(book1, book2, book3)
|
|
author2.favorite_books.add(book1)
|
|
author3.favorite_books.add(book2)
|
|
author4.favorite_books.add(book3)
|
|
|
|
def test_bug(self):
|
|
list(Author2.objects.prefetch_related("first_book", "favorite_books"))
|
|
|
|
|
|
class Ticket21760Tests(TestCase):
|
|
@classmethod
|
|
def setUpTestData(cls):
|
|
cls.rooms = []
|
|
for _ in range(3):
|
|
house = House.objects.create()
|
|
for _ in range(3):
|
|
cls.rooms.append(Room.objects.create(house=house))
|
|
# Set main_room for each house before creating the next one for
|
|
# databases where supports_nullable_unique_constraints is False.
|
|
house.main_room = cls.rooms[-3]
|
|
house.save()
|
|
|
|
def test_bug(self):
|
|
prefetcher = get_prefetcher(self.rooms[0], "house", "house")[0]
|
|
queryset = prefetcher.get_prefetch_queryset(list(Room.objects.all()))[0]
|
|
self.assertNotIn(" JOIN ", str(queryset.query))
|
|
|
|
|
|
class DirectPrefetchedObjectCacheReuseTests(TestCase):
|
|
"""
|
|
prefetch_related() reuses objects fetched in _prefetched_objects_cache.
|
|
|
|
When objects are prefetched and not stored as an instance attribute (often
|
|
intermediary relationships), they are saved to the
|
|
_prefetched_objects_cache attribute. prefetch_related() takes
|
|
_prefetched_objects_cache into account when determining whether an object
|
|
has been fetched[1] and retrieves results from it when it is populated [2].
|
|
|
|
[1]: #25546 (duplicate queries on nested Prefetch)
|
|
[2]: #27554 (queryset evaluation fails with a mix of nested and flattened
|
|
prefetches)
|
|
"""
|
|
|
|
@classmethod
|
|
def setUpTestData(cls):
|
|
cls.book1, cls.book2 = [
|
|
Book.objects.create(title="book1"),
|
|
Book.objects.create(title="book2"),
|
|
]
|
|
cls.author11, cls.author12, cls.author21 = [
|
|
Author.objects.create(first_book=cls.book1, name="Author11"),
|
|
Author.objects.create(first_book=cls.book1, name="Author12"),
|
|
Author.objects.create(first_book=cls.book2, name="Author21"),
|
|
]
|
|
cls.author1_address1, cls.author1_address2, cls.author2_address1 = [
|
|
AuthorAddress.objects.create(author=cls.author11, address="Happy place"),
|
|
AuthorAddress.objects.create(author=cls.author12, address="Haunted house"),
|
|
AuthorAddress.objects.create(author=cls.author21, address="Happy place"),
|
|
]
|
|
cls.bookwithyear1 = BookWithYear.objects.create(
|
|
title="Poems", published_year=2010
|
|
)
|
|
cls.bookreview1 = BookReview.objects.create(book=cls.bookwithyear1)
|
|
|
|
def test_detect_is_fetched(self):
|
|
"""
|
|
Nested prefetch_related() shouldn't trigger duplicate queries for the same
|
|
lookup.
|
|
"""
|
|
with self.assertNumQueries(3):
|
|
books = Book.objects.filter(title__in=["book1", "book2"],).prefetch_related(
|
|
Prefetch(
|
|
"first_time_authors",
|
|
Author.objects.prefetch_related(
|
|
Prefetch(
|
|
"addresses",
|
|
AuthorAddress.objects.filter(address="Happy place"),
|
|
)
|
|
),
|
|
),
|
|
)
|
|
book1, book2 = list(books)
|
|
|
|
with self.assertNumQueries(0):
|
|
self.assertSequenceEqual(
|
|
book1.first_time_authors.all(), [self.author11, self.author12]
|
|
)
|
|
self.assertSequenceEqual(book2.first_time_authors.all(), [self.author21])
|
|
|
|
self.assertSequenceEqual(
|
|
book1.first_time_authors.all()[0].addresses.all(),
|
|
[self.author1_address1],
|
|
)
|
|
self.assertSequenceEqual(
|
|
book1.first_time_authors.all()[1].addresses.all(), []
|
|
)
|
|
self.assertSequenceEqual(
|
|
book2.first_time_authors.all()[0].addresses.all(),
|
|
[self.author2_address1],
|
|
)
|
|
|
|
self.assertEqual(
|
|
list(book1.first_time_authors.all()),
|
|
list(book1.first_time_authors.all().all()),
|
|
)
|
|
self.assertEqual(
|
|
list(book2.first_time_authors.all()),
|
|
list(book2.first_time_authors.all().all()),
|
|
)
|
|
self.assertEqual(
|
|
list(book1.first_time_authors.all()[0].addresses.all()),
|
|
list(book1.first_time_authors.all()[0].addresses.all().all()),
|
|
)
|
|
self.assertEqual(
|
|
list(book1.first_time_authors.all()[1].addresses.all()),
|
|
list(book1.first_time_authors.all()[1].addresses.all().all()),
|
|
)
|
|
self.assertEqual(
|
|
list(book2.first_time_authors.all()[0].addresses.all()),
|
|
list(book2.first_time_authors.all()[0].addresses.all().all()),
|
|
)
|
|
|
|
def test_detect_is_fetched_with_to_attr(self):
|
|
with self.assertNumQueries(3):
|
|
books = Book.objects.filter(title__in=["book1", "book2"],).prefetch_related(
|
|
Prefetch(
|
|
"first_time_authors",
|
|
Author.objects.prefetch_related(
|
|
Prefetch(
|
|
"addresses",
|
|
AuthorAddress.objects.filter(address="Happy place"),
|
|
to_attr="happy_place",
|
|
)
|
|
),
|
|
to_attr="first_authors",
|
|
),
|
|
)
|
|
book1, book2 = list(books)
|
|
|
|
with self.assertNumQueries(0):
|
|
self.assertEqual(book1.first_authors, [self.author11, self.author12])
|
|
self.assertEqual(book2.first_authors, [self.author21])
|
|
|
|
self.assertEqual(
|
|
book1.first_authors[0].happy_place, [self.author1_address1]
|
|
)
|
|
self.assertEqual(book1.first_authors[1].happy_place, [])
|
|
self.assertEqual(
|
|
book2.first_authors[0].happy_place, [self.author2_address1]
|
|
)
|
|
|
|
def test_prefetch_reverse_foreign_key(self):
|
|
with self.assertNumQueries(2):
|
|
(bookwithyear1,) = BookWithYear.objects.prefetch_related("bookreview_set")
|
|
with self.assertNumQueries(0):
|
|
self.assertCountEqual(
|
|
bookwithyear1.bookreview_set.all(), [self.bookreview1]
|
|
)
|
|
with self.assertNumQueries(0):
|
|
prefetch_related_objects([bookwithyear1], "bookreview_set")
|
|
|
|
def test_add_clears_prefetched_objects(self):
|
|
bookwithyear = BookWithYear.objects.get(pk=self.bookwithyear1.pk)
|
|
prefetch_related_objects([bookwithyear], "bookreview_set")
|
|
self.assertCountEqual(bookwithyear.bookreview_set.all(), [self.bookreview1])
|
|
new_review = BookReview.objects.create()
|
|
bookwithyear.bookreview_set.add(new_review)
|
|
self.assertCountEqual(
|
|
bookwithyear.bookreview_set.all(), [self.bookreview1, new_review]
|
|
)
|
|
|
|
def test_remove_clears_prefetched_objects(self):
|
|
bookwithyear = BookWithYear.objects.get(pk=self.bookwithyear1.pk)
|
|
prefetch_related_objects([bookwithyear], "bookreview_set")
|
|
self.assertCountEqual(bookwithyear.bookreview_set.all(), [self.bookreview1])
|
|
bookwithyear.bookreview_set.remove(self.bookreview1)
|
|
self.assertCountEqual(bookwithyear.bookreview_set.all(), [])
|
|
|
|
|
|
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.assertSequenceEqual(authors, [self.author1, self.author2])
|