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django/tests/prefetch_related/tests.py
Nick Pope 847f46e9bf
Removed redundant QuerySet.all() calls in docs and tests.
Most QuerySet methods are mapped onto the Manager and, in general,
it isn't necessary to call .all() on the manager.
2022-02-22 10:29:38 +01:00

1911 lines
74 KiB
Python

from unittest import mock
from django.contrib.contenttypes.models import ContentType
from django.core.exceptions import ObjectDoesNotExist
from django.db import connection
from django.db.models import Prefetch, QuerySet, prefetch_related_objects
from django.db.models.query import get_prefetcher
from django.db.models.sql import Query
from django.test import TestCase, override_settings
from django.test.utils import CaptureQueriesContext, ignore_warnings
from django.utils.deprecation import RemovedInDjango50Warning
from .models import (
Article,
Author,
Author2,
AuthorAddress,
AuthorWithAge,
Bio,
Book,
Bookmark,
BookReview,
BookWithYear,
Comment,
Department,
Employee,
FavoriteAuthors,
House,
LessonEntry,
ModelIterableSubclass,
Person,
Qualification,
Reader,
Room,
TaggedItem,
Teacher,
WordEntry,
)
class TestDataMixin:
@classmethod
def setUpTestData(cls):
cls.book1 = Book.objects.create(title="Poems")
cls.book2 = Book.objects.create(title="Jane Eyre")
cls.book3 = Book.objects.create(title="Wuthering Heights")
cls.book4 = Book.objects.create(title="Sense and Sensibility")
cls.author1 = Author.objects.create(name="Charlotte", first_book=cls.book1)
cls.author2 = Author.objects.create(name="Anne", first_book=cls.book1)
cls.author3 = Author.objects.create(name="Emily", first_book=cls.book1)
cls.author4 = Author.objects.create(name="Jane", first_book=cls.book4)
cls.book1.authors.add(cls.author1, cls.author2, cls.author3)
cls.book2.authors.add(cls.author1)
cls.book3.authors.add(cls.author3)
cls.book4.authors.add(cls.author4)
cls.reader1 = Reader.objects.create(name="Amy")
cls.reader2 = Reader.objects.create(name="Belinda")
cls.reader1.books_read.add(cls.book1, cls.book4)
cls.reader2.books_read.add(cls.book2, cls.book4)
class PrefetchRelatedTests(TestDataMixin, TestCase):
def assertWhereContains(self, sql, needle):
where_idx = sql.index("WHERE")
self.assertEqual(
sql.count(str(needle), where_idx),
1,
msg="WHERE clause doesn't contain %s, actual SQL: %s"
% (needle, sql[where_idx:]),
)
def test_m2m_forward(self):
with self.assertNumQueries(2):
lists = [
list(b.authors.all()) for b in Book.objects.prefetch_related("authors")
]
normal_lists = [list(b.authors.all()) for b in Book.objects.all()]
self.assertEqual(lists, normal_lists)
def test_m2m_reverse(self):
with self.assertNumQueries(2):
lists = [
list(a.books.all()) for a in Author.objects.prefetch_related("books")
]
normal_lists = [list(a.books.all()) for a in Author.objects.all()]
self.assertEqual(lists, normal_lists)
def test_foreignkey_forward(self):
with self.assertNumQueries(2):
books = [
a.first_book for a in Author.objects.prefetch_related("first_book")
]
normal_books = [a.first_book for a in Author.objects.all()]
self.assertEqual(books, normal_books)
def test_foreignkey_reverse(self):
with self.assertNumQueries(2):
[
list(b.first_time_authors.all())
for b in Book.objects.prefetch_related("first_time_authors")
]
self.assertSequenceEqual(self.book2.authors.all(), [self.author1])
def test_onetoone_reverse_no_match(self):
# Regression for #17439
with self.assertNumQueries(2):
book = Book.objects.prefetch_related("bookwithyear").all()[0]
with self.assertNumQueries(0):
with self.assertRaises(BookWithYear.DoesNotExist):
book.bookwithyear
def test_onetoone_reverse_with_to_field_pk(self):
"""
A model (Bio) with a OneToOneField primary key (author) that references
a non-pk field (name) on the related model (Author) is prefetchable.
"""
Bio.objects.bulk_create(
[
Bio(author=self.author1),
Bio(author=self.author2),
Bio(author=self.author3),
]
)
authors = Author.objects.filter(
name__in=[self.author1, self.author2, self.author3],
).prefetch_related("bio")
with self.assertNumQueries(2):
for author in authors:
self.assertEqual(author.name, author.bio.author.name)
def test_survives_clone(self):
with self.assertNumQueries(2):
[
list(b.first_time_authors.all())
for b in Book.objects.prefetch_related("first_time_authors").exclude(
id=1000
)
]
def test_len(self):
with self.assertNumQueries(2):
qs = Book.objects.prefetch_related("first_time_authors")
len(qs)
[list(b.first_time_authors.all()) for b in qs]
def test_bool(self):
with self.assertNumQueries(2):
qs = Book.objects.prefetch_related("first_time_authors")
bool(qs)
[list(b.first_time_authors.all()) for b in qs]
def test_count(self):
with self.assertNumQueries(2):
qs = Book.objects.prefetch_related("first_time_authors")
[b.first_time_authors.count() for b in qs]
def test_exists(self):
with self.assertNumQueries(2):
qs = Book.objects.prefetch_related("first_time_authors")
[b.first_time_authors.exists() for b in qs]
def test_in_and_prefetch_related(self):
"""
Regression test for #20242 - QuerySet "in" didn't work the first time
when using prefetch_related. This was fixed by the removal of chunked
reads from QuerySet iteration in
70679243d1786e03557c28929f9762a119e3ac14.
"""
qs = Book.objects.prefetch_related("first_time_authors")
self.assertIn(qs[0], qs)
def test_clear(self):
with self.assertNumQueries(5):
with_prefetch = Author.objects.prefetch_related("books")
without_prefetch = with_prefetch.prefetch_related(None)
[list(a.books.all()) for a in without_prefetch]
def test_m2m_then_m2m(self):
"""A m2m can be followed through another m2m."""
with self.assertNumQueries(3):
qs = Author.objects.prefetch_related("books__read_by")
lists = [
[[str(r) for r in b.read_by.all()] for b in a.books.all()] for a in qs
]
self.assertEqual(
lists,
[
[["Amy"], ["Belinda"]], # Charlotte - Poems, Jane Eyre
[["Amy"]], # Anne - Poems
[["Amy"], []], # Emily - Poems, Wuthering Heights
[["Amy", "Belinda"]], # Jane - Sense and Sense
],
)
def test_overriding_prefetch(self):
with self.assertNumQueries(3):
qs = Author.objects.prefetch_related("books", "books__read_by")
lists = [
[[str(r) for r in b.read_by.all()] for b in a.books.all()] for a in qs
]
self.assertEqual(
lists,
[
[["Amy"], ["Belinda"]], # Charlotte - Poems, Jane Eyre
[["Amy"]], # Anne - Poems
[["Amy"], []], # Emily - Poems, Wuthering Heights
[["Amy", "Belinda"]], # Jane - Sense and Sense
],
)
with self.assertNumQueries(3):
qs = Author.objects.prefetch_related("books__read_by", "books")
lists = [
[[str(r) for r in b.read_by.all()] for b in a.books.all()] for a in qs
]
self.assertEqual(
lists,
[
[["Amy"], ["Belinda"]], # Charlotte - Poems, Jane Eyre
[["Amy"]], # Anne - Poems
[["Amy"], []], # Emily - Poems, Wuthering Heights
[["Amy", "Belinda"]], # Jane - Sense and Sense
],
)
def test_get(self):
"""
Objects retrieved with .get() get the prefetch behavior.
"""
# Need a double
with self.assertNumQueries(3):
author = Author.objects.prefetch_related("books__read_by").get(
name="Charlotte"
)
lists = [[str(r) for r in b.read_by.all()] for b in author.books.all()]
self.assertEqual(lists, [["Amy"], ["Belinda"]]) # Poems, Jane Eyre
def test_foreign_key_then_m2m(self):
"""
A m2m relation can be followed after a relation like ForeignKey that
doesn't have many objects.
"""
with self.assertNumQueries(2):
qs = Author.objects.select_related("first_book").prefetch_related(
"first_book__read_by"
)
lists = [[str(r) for r in a.first_book.read_by.all()] for a in qs]
self.assertEqual(lists, [["Amy"], ["Amy"], ["Amy"], ["Amy", "Belinda"]])
def test_reverse_one_to_one_then_m2m(self):
"""
A m2m relation can be followed after going through the select_related
reverse of an o2o.
"""
qs = Author.objects.prefetch_related("bio__books").select_related("bio")
with self.assertNumQueries(1):
list(qs.all())
Bio.objects.create(author=self.author1)
with self.assertNumQueries(2):
list(qs.all())
def test_attribute_error(self):
qs = Reader.objects.prefetch_related("books_read__xyz")
msg = (
"Cannot find 'xyz' on Book object, 'books_read__xyz' "
"is an invalid parameter to prefetch_related()"
)
with self.assertRaisesMessage(AttributeError, msg) as cm:
list(qs)
self.assertIn("prefetch_related", str(cm.exception))
def test_invalid_final_lookup(self):
qs = Book.objects.prefetch_related("authors__name")
msg = (
"'authors__name' does not resolve to an item that supports "
"prefetching - this is an invalid parameter to prefetch_related()."
)
with self.assertRaisesMessage(ValueError, msg) as cm:
list(qs)
self.assertIn("prefetch_related", str(cm.exception))
self.assertIn("name", str(cm.exception))
def test_prefetch_eq(self):
prefetch_1 = Prefetch("authors", queryset=Author.objects.all())
prefetch_2 = Prefetch("books", queryset=Book.objects.all())
self.assertEqual(prefetch_1, prefetch_1)
self.assertEqual(prefetch_1, mock.ANY)
self.assertNotEqual(prefetch_1, prefetch_2)
def test_forward_m2m_to_attr_conflict(self):
msg = "to_attr=authors conflicts with a field on the Book model."
authors = Author.objects.all()
with self.assertRaisesMessage(ValueError, msg):
list(
Book.objects.prefetch_related(
Prefetch("authors", queryset=authors, to_attr="authors"),
)
)
# Without the ValueError, an author was deleted due to the implicit
# save of the relation assignment.
self.assertEqual(self.book1.authors.count(), 3)
def test_reverse_m2m_to_attr_conflict(self):
msg = "to_attr=books conflicts with a field on the Author model."
poems = Book.objects.filter(title="Poems")
with self.assertRaisesMessage(ValueError, msg):
list(
Author.objects.prefetch_related(
Prefetch("books", queryset=poems, to_attr="books"),
)
)
# Without the ValueError, a book was deleted due to the implicit
# save of reverse relation assignment.
self.assertEqual(self.author1.books.count(), 2)
def test_m2m_then_reverse_fk_object_ids(self):
with CaptureQueriesContext(connection) as queries:
list(Book.objects.prefetch_related("authors__addresses"))
sql = queries[-1]["sql"]
self.assertWhereContains(sql, self.author1.name)
def test_m2m_then_m2m_object_ids(self):
with CaptureQueriesContext(connection) as queries:
list(Book.objects.prefetch_related("authors__favorite_authors"))
sql = queries[-1]["sql"]
self.assertWhereContains(sql, self.author1.name)
def test_m2m_then_reverse_one_to_one_object_ids(self):
with CaptureQueriesContext(connection) as queries:
list(Book.objects.prefetch_related("authors__authorwithage"))
sql = queries[-1]["sql"]
self.assertWhereContains(sql, self.author1.id)
def test_filter_deferred(self):
"""
Related filtering of prefetched querysets is deferred on m2m and
reverse m2o relations until necessary.
"""
add_q = Query.add_q
for relation in ["authors", "first_time_authors"]:
with self.subTest(relation=relation):
with mock.patch.object(
Query,
"add_q",
autospec=True,
side_effect=lambda self, q: add_q(self, q),
) as add_q_mock:
list(Book.objects.prefetch_related(relation))
self.assertEqual(add_q_mock.call_count, 1)
def test_named_values_list(self):
qs = Author.objects.prefetch_related("books")
self.assertCountEqual(
[value.name for value in qs.values_list("name", named=True)],
["Anne", "Charlotte", "Emily", "Jane"],
)
def test_m2m_prefetching_iterator_with_chunks(self):
with self.assertNumQueries(3):
authors = [
b.authors.first()
for b in Book.objects.prefetch_related("authors").iterator(chunk_size=2)
]
self.assertEqual(
authors,
[self.author1, self.author1, self.author3, self.author4],
)
@ignore_warnings(category=RemovedInDjango50Warning)
def test_m2m_prefetching_iterator_without_chunks(self):
# prefetch_related() is ignored.
with self.assertNumQueries(5):
authors = [
b.authors.first()
for b in Book.objects.prefetch_related("authors").iterator()
]
self.assertEqual(
authors,
[self.author1, self.author1, self.author3, self.author4],
)
def test_m2m_prefetching_iterator_without_chunks_warning(self):
msg = (
"Using QuerySet.iterator() after prefetch_related() without "
"specifying chunk_size is deprecated."
)
with self.assertWarnsMessage(RemovedInDjango50Warning, msg):
Book.objects.prefetch_related("authors").iterator()
class RawQuerySetTests(TestDataMixin, TestCase):
def test_basic(self):
with self.assertNumQueries(2):
books = Book.objects.raw(
"SELECT * FROM prefetch_related_book WHERE id = %s", (self.book1.id,)
).prefetch_related("authors")
book1 = list(books)[0]
with self.assertNumQueries(0):
self.assertCountEqual(
book1.authors.all(), [self.author1, self.author2, self.author3]
)
def test_prefetch_before_raw(self):
with self.assertNumQueries(2):
books = Book.objects.prefetch_related("authors").raw(
"SELECT * FROM prefetch_related_book WHERE id = %s", (self.book1.id,)
)
book1 = list(books)[0]
with self.assertNumQueries(0):
self.assertCountEqual(
book1.authors.all(), [self.author1, self.author2, self.author3]
)
def test_clear(self):
with self.assertNumQueries(5):
with_prefetch = Author.objects.raw(
"SELECT * FROM prefetch_related_author"
).prefetch_related("books")
without_prefetch = with_prefetch.prefetch_related(None)
[list(a.books.all()) for a in without_prefetch]
class CustomPrefetchTests(TestCase):
@classmethod
def traverse_qs(cls, obj_iter, path):
"""
Helper method that returns a list containing a list of the objects in the
obj_iter. Then for each object in the obj_iter, the path will be
recursively travelled and the found objects are added to the return value.
"""
ret_val = []
if hasattr(obj_iter, "all"):
obj_iter = obj_iter.all()
try:
iter(obj_iter)
except TypeError:
obj_iter = [obj_iter]
for obj in obj_iter:
rel_objs = []
for part in path:
if not part:
continue
try:
related = getattr(obj, part[0])
except ObjectDoesNotExist:
continue
if related is not None:
rel_objs.extend(cls.traverse_qs(related, [part[1:]]))
ret_val.append((obj, rel_objs))
return ret_val
@classmethod
def setUpTestData(cls):
cls.person1 = Person.objects.create(name="Joe")
cls.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.
cls.house1 = House.objects.create(
name="House 1", address="123 Main St", owner=cls.person1
)
cls.room1_1 = Room.objects.create(name="Dining room", house=cls.house1)
cls.room1_2 = Room.objects.create(name="Lounge", house=cls.house1)
cls.room1_3 = Room.objects.create(name="Kitchen", house=cls.house1)
cls.house1.main_room = cls.room1_1
cls.house1.save()
cls.person1.houses.add(cls.house1)
cls.house2 = House.objects.create(
name="House 2", address="45 Side St", owner=cls.person1
)
cls.room2_1 = Room.objects.create(name="Dining room", house=cls.house2)
cls.room2_2 = Room.objects.create(name="Lounge", house=cls.house2)
cls.room2_3 = Room.objects.create(name="Kitchen", house=cls.house2)
cls.house2.main_room = cls.room2_1
cls.house2.save()
cls.person1.houses.add(cls.house2)
cls.house3 = House.objects.create(
name="House 3", address="6 Downing St", owner=cls.person2
)
cls.room3_1 = Room.objects.create(name="Dining room", house=cls.house3)
cls.room3_2 = Room.objects.create(name="Lounge", house=cls.house3)
cls.room3_3 = Room.objects.create(name="Kitchen", house=cls.house3)
cls.house3.main_room = cls.room3_1
cls.house3.save()
cls.person2.houses.add(cls.house3)
cls.house4 = House.objects.create(
name="house 4", address="7 Regents St", owner=cls.person2
)
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.prefetch_related("house")
lst1 = self.traverse_qs(rooms, [["house", "owner"]])
with self.assertNumQueries(2):
rooms = Room.objects.prefetch_related(Prefetch("house", queryset=houses))
lst2 = self.traverse_qs(rooms, [["house", "owner"]])
self.assertEqual(lst1, lst2)
with self.assertNumQueries(2):
houses = House.objects.select_related("owner")
rooms = Room.objects.prefetch_related(
Prefetch("house", queryset=houses, to_attr="house_attr")
)
lst2 = self.traverse_qs(rooms, [["house_attr", "owner"]])
self.assertEqual(lst1, lst2)
room = Room.objects.prefetch_related(
Prefetch("house", queryset=houses.filter(address="DoesNotExist"))
).first()
with self.assertRaises(ObjectDoesNotExist):
getattr(room, "house")
room = Room.objects.prefetch_related(
Prefetch(
"house",
queryset=houses.filter(address="DoesNotExist"),
to_attr="house_attr",
)
).first()
self.assertIsNone(room.house_attr)
rooms = Room.objects.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.prefetch_related("main_room_of")
lst1 = self.traverse_qs(rooms, [["main_room_of", "owner"]])
with self.assertNumQueries(2):
rooms = Room.objects.prefetch_related(
Prefetch("main_room_of", queryset=houses)
)
lst2 = self.traverse_qs(rooms, [["main_room_of", "owner"]])
self.assertEqual(lst1, lst2)
with self.assertNumQueries(2):
rooms = list(
Room.objects.prefetch_related(
Prefetch(
"main_room_of",
queryset=houses,
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.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)]),
],
)
def test_m2m_manager_reused(self):
author = Author.objects.prefetch_related(
"favorite_authors",
"favors_me",
).first()
self.assertIs(author.favorite_authors, author.favorite_authors)
self.assertIs(author.favors_me, author.favors_me)
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 ()\n" "Sense 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])
class NestedPrefetchTests(TestCase):
@classmethod
def setUpTestData(cls):
house = House.objects.create(name="Big house", address="123 Main St")
cls.room = Room.objects.create(name="Kitchen", house=house)
def test_nested_prefetch_is_not_overwritten_by_related_object(self):
"""
The prefetched relationship is used rather than populating the reverse
relationship from the parent, when prefetching a set of child objects
related to a set of parent objects and the child queryset itself
specifies a prefetch back to the parent.
"""
queryset = House.objects.only("name").prefetch_related(
Prefetch(
"rooms",
queryset=Room.objects.prefetch_related(
Prefetch("house", queryset=House.objects.only("address")),
),
),
)
with self.assertNumQueries(3):
house = queryset.first()
self.assertIs(Room.house.is_cached(self.room), True)
with self.assertNumQueries(0):
house.rooms.first().house.address