django/tests/modeltests/prefetch_related/tests.py

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from __future__ import with_statement, absolute_import
from django.contrib.contenttypes.models import ContentType
from django.test import TestCase
from .models import (Author, Book, Reader, Qualification, Teacher, Department,
TaggedItem, Bookmark, AuthorAddress, FavoriteAuthors, AuthorWithAge,
BookWithYear, Person, House, Room, Employee)
class PrefetchRelatedTests(TestCase):
def setUp(self):
self.book1 = Book.objects.create(title="Poems")
self.book2 = Book.objects.create(title="Jane Eyre")
self.book3 = Book.objects.create(title="Wuthering Heights")
self.book4 = Book.objects.create(title="Sense and Sensibility")
self.author1 = Author.objects.create(name="Charlotte",
first_book=self.book1)
self.author2 = Author.objects.create(name="Anne",
first_book=self.book1)
self.author3 = Author.objects.create(name="Emily",
first_book=self.book1)
self.author4 = Author.objects.create(name="Jane",
first_book=self.book4)
self.book1.authors.add(self.author1, self.author2, self.author3)
self.book2.authors.add(self.author1)
self.book3.authors.add(self.author3)
self.book4.authors.add(self.author4)
self.reader1 = Reader.objects.create(name="Amy")
self.reader2 = Reader.objects.create(name="Belinda")
self.reader1.books_read.add(self.book1, self.book4)
self.reader2.books_read.add(self.book2, self.book4)
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):
lists = [list(b.first_time_authors.all())
for b in Book.objects.prefetch_related('first_time_authors')]
self.assertQuerysetEqual(self.book2.authors.all(), [u"<Author: Charlotte>"])
def test_survives_clone(self):
with self.assertNumQueries(2):
lists = [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')
length = len(qs)
lists = [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')
x = bool(qs)
lists = [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_clear(self):
"""
Test that we can clear the behavior by calling prefetch_related()
"""
with self.assertNumQueries(5):
with_prefetch = Author.objects.prefetch_related('books')
without_prefetch = with_prefetch.prefetch_related(None)
lists = [list(a.books.all()) for a in without_prefetch]
def test_m2m_then_m2m(self):
"""
Test we can follow a m2m and another m2m
"""
with self.assertNumQueries(3):
qs = Author.objects.prefetch_related('books__read_by')
lists = [[[unicode(r) for r in b.read_by.all()]
for b in a.books.all()]
for a in qs]
self.assertEqual(lists,
[
[[u"Amy"], [u"Belinda"]], # Charlotte - Poems, Jane Eyre
[[u"Amy"]], # Anne - Poems
[[u"Amy"], []], # Emily - Poems, Wuthering Heights
[[u"Amy", u"Belinda"]], # Jane - Sense and Sense
])
def test_overriding_prefetch(self):
with self.assertNumQueries(3):
qs = Author.objects.prefetch_related('books', 'books__read_by')
lists = [[[unicode(r) for r in b.read_by.all()]
for b in a.books.all()]
for a in qs]
self.assertEqual(lists,
[
[[u"Amy"], [u"Belinda"]], # Charlotte - Poems, Jane Eyre
[[u"Amy"]], # Anne - Poems
[[u"Amy"], []], # Emily - Poems, Wuthering Heights
[[u"Amy", u"Belinda"]], # Jane - Sense and Sense
])
with self.assertNumQueries(3):
qs = Author.objects.prefetch_related('books__read_by', 'books')
lists = [[[unicode(r) for r in b.read_by.all()]
for b in a.books.all()]
for a in qs]
self.assertEqual(lists,
[
[[u"Amy"], [u"Belinda"]], # Charlotte - Poems, Jane Eyre
[[u"Amy"]], # Anne - Poems
[[u"Amy"], []], # Emily - Poems, Wuthering Heights
[[u"Amy", u"Belinda"]], # Jane - Sense and Sense
])
def test_get(self):
"""
Test that 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 = [[unicode(r) for r in b.read_by.all()]
for b in author.books.all()]
self.assertEqual(lists, [[u"Amy"], [u"Belinda"]]) # Poems, Jane Eyre
def test_foreign_key_then_m2m(self):
"""
Test we can follow an m2m relation 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 = [[unicode(r) for r in a.first_book.read_by.all()]
for a in qs]
self.assertEqual(lists, [[u"Amy"],
[u"Amy"],
[u"Amy"],
[u"Amy", "Belinda"]])
def test_attribute_error(self):
qs = Reader.objects.all().prefetch_related('books_read__xyz')
with self.assertRaises(AttributeError) as cm:
list(qs)
self.assertTrue('prefetch_related' in str(cm.exception))
def test_invalid_final_lookup(self):
qs = Book.objects.prefetch_related('authors__name')
with self.assertRaises(ValueError) as cm:
list(qs)
self.assertTrue('prefetch_related' in str(cm.exception))
self.assertTrue("name" in str(cm.exception))
class DefaultManagerTests(TestCase):
def setUp(self):
self.qual1 = Qualification.objects.create(name="BA")
self.qual2 = Qualification.objects.create(name="BSci")
self.qual3 = Qualification.objects.create(name="MA")
self.qual4 = Qualification.objects.create(name="PhD")
self.teacher1 = Teacher.objects.create(name="Mr Cleese")
self.teacher2 = Teacher.objects.create(name="Mr Idle")
self.teacher3 = Teacher.objects.create(name="Mr Chapman")
self.teacher1.qualifications.add(self.qual1, self.qual2, self.qual3, self.qual4)
self.teacher2.qualifications.add(self.qual1)
self.teacher3.qualifications.add(self.qual2)
self.dept1 = Department.objects.create(name="English")
self.dept2 = Department.objects.create(name="Physics")
self.dept1.teachers.add(self.teacher1, self.teacher2)
self.dept2.teachers.add(self.teacher1, self.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(unicode(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):
def setUp(self):
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)
self.book1, self.book2, self.book3 = book1, book2, book3
self.reader1, self.reader2, self.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="stupid", 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_traverse_GFK(self):
"""
Test that we can traverse a 'content_object' 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 = set([r.name for tag in qs
for r in tag.content_object.read_by.all()])
self.assertEqual(readers_of_awesome_books, set(["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):
b = Bookmark.objects.create(url='http://www.djangoproject.com/')
t1 = TaggedItem.objects.create(content_object=b, tag='django')
t2 = TaggedItem.objects.create(content_object=b, 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"])
class MultiTableInheritanceTest(TestCase):
def setUp(self):
self.book1 = BookWithYear.objects.create(
title="Poems", published_year=2010)
self.book2 = BookWithYear.objects.create(
title="More poems", published_year=2011)
self.author1 = AuthorWithAge.objects.create(
name='Jane', first_book=self.book1, age=50)
self.author2 = AuthorWithAge.objects.create(
name='Tom', first_book=self.book1, age=49)
self.author3 = AuthorWithAge.objects.create(
name='Robert', first_book=self.book2, age=48)
self.authorAddress = AuthorAddress.objects.create(
author=self.author1, address='SomeStreet 1')
self.book2.aged_authors.add(self.author2, self.author3)
def test_foreignkey(self):
with self.assertNumQueries(2):
qs = AuthorWithAge.objects.prefetch_related('addresses')
addresses = [[unicode(address) for address in obj.addresses.all()]
for obj in qs]
self.assertEquals(addresses, [[unicode(self.authorAddress)], [], []])
def test_m2m_to_inheriting_model(self):
qs = AuthorWithAge.objects.prefetch_related('books_with_year')
with self.assertNumQueries(2):
lst = [[unicode(book) for book in author.books_with_year.all()]
for author in qs]
qs = AuthorWithAge.objects.all()
lst2 = [[unicode(book) for book in author.books_with_year.all()]
for author in qs]
self.assertEquals(lst, lst2)
qs = BookWithYear.objects.prefetch_related('aged_authors')
with self.assertNumQueries(2):
lst = [[unicode(author) for author in book.aged_authors.all()]
for book in qs]
qs = BookWithYear.objects.all()
lst2 = [[unicode(author) for author in book.aged_authors.all()]
for book in qs]
self.assertEquals(lst, lst2)
def test_parent_link_prefetch(self):
with self.assertNumQueries(2):
[a.author for a in AuthorWithAge.objects.prefetch_related('author')]
def test_child_link_prefetch(self):
with self.assertNumQueries(2):
l = [a.authorwithage for a in Author.objects.prefetch_related('authorwithage')]
self.assertEqual(l, [a.authorwithage for a in Author.objects.all()])
class ForeignKeyToFieldTest(TestCase):
def setUp(self):
self.book = Book.objects.create(title="Poems")
self.author1 = Author.objects.create(name='Jane', first_book=self.book)
self.author2 = Author.objects.create(name='Tom', first_book=self.book)
self.author3 = Author.objects.create(name='Robert', first_book=self.book)
self.authorAddress = AuthorAddress.objects.create(
author=self.author1, address='SomeStreet 1'
)
FavoriteAuthors.objects.create(author=self.author1,
likes_author=self.author2)
FavoriteAuthors.objects.create(author=self.author2,
likes_author=self.author3)
FavoriteAuthors.objects.create(author=self.author3,
likes_author=self.author1)
def test_foreignkey(self):
with self.assertNumQueries(2):
qs = Author.objects.prefetch_related('addresses')
addresses = [[unicode(address) for address in obj.addresses.all()]
for obj in qs]
self.assertEquals(addresses, [[unicode(self.authorAddress)], [], []])
def test_m2m(self):
with self.assertNumQueries(3):
qs = Author.objects.all().prefetch_related('favorite_authors', 'favors_me')
favorites = [(
[unicode(i_like) for i_like in author.favorite_authors.all()],
[unicode(likes_me) for likes_me in author.favors_me.all()]
) for author in qs]
self.assertEquals(
favorites,
[
([unicode(self.author2)],[unicode(self.author3)]),
([unicode(self.author3)],[unicode(self.author1)]),
([unicode(self.author1)],[unicode(self.author2)])
]
)
class LookupOrderingTest(TestCase):
"""
Test cases that demonstrate that ordering of lookups is important, and
ensure it is preserved.
"""
def setUp(self):
self.person1 = Person.objects.create(name="Joe")
self.person2 = Person.objects.create(name="Mary")
self.house1 = House.objects.create(address="123 Main St")
self.house2 = House.objects.create(address="45 Side St")
self.house3 = House.objects.create(address="6 Downing St")
self.house4 = House.objects.create(address="7 Regents St")
self.room1_1 = Room.objects.create(name="Dining room", house=self.house1)
self.room1_2 = Room.objects.create(name="Lounge", house=self.house1)
self.room1_3 = Room.objects.create(name="Kitchen", house=self.house1)
self.room2_1 = Room.objects.create(name="Dining room", house=self.house2)
self.room2_2 = Room.objects.create(name="Lounge", house=self.house2)
self.room3_1 = Room.objects.create(name="Dining room", house=self.house3)
self.room3_2 = Room.objects.create(name="Lounge", house=self.house3)
self.room3_3 = Room.objects.create(name="Kitchen", house=self.house3)
self.room4_1 = Room.objects.create(name="Dining room", house=self.house4)
self.room4_2 = Room.objects.create(name="Lounge", house=self.house4)
self.person1.houses.add(self.house1, self.house2)
self.person2.houses.add(self.house3, self.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):
def setUp(self):
boss = Employee.objects.create(name="Peter")
worker1 = Employee.objects.create(name="Joe", boss=boss)
worker2 = 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)