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Fixed #27719 -- Added QuerySet.alias() to allow creating reusable aliases.
QuerySet.alias() allows creating reusable aliases for expressions that don't need to be selected but are used for filtering, ordering, or as a part of complex expressions. Thanks Simon Charette for reviews.
This commit is contained in:
Alexandr Tatarinov
Mariusz Felisiak
parent
88af11c58b
commit
f4ac167119
8 changed files with 294 additions and 6 deletions
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@ -10,7 +10,7 @@ from django.db.models import (
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Subquery, Sum, Value, When,
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)
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from django.db.models.expressions import RawSQL
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from django.db.models.functions import Length, Lower
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from django.db.models.functions import Coalesce, Length, Lower
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from django.test import TestCase, skipUnlessDBFeature
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from .models import (
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@ -664,3 +664,225 @@ class NonAggregateAnnotationTestCase(TestCase):
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{'name': 'Paul Bissex', 'max_pages': 0},
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{'name': 'Wesley J. Chun', 'max_pages': 0},
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])
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class AliasTests(TestCase):
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@classmethod
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def setUpTestData(cls):
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cls.a1 = Author.objects.create(name='Adrian Holovaty', age=34)
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cls.a2 = Author.objects.create(name='Jacob Kaplan-Moss', age=35)
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cls.a3 = Author.objects.create(name='James Bennett', age=34)
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cls.a4 = Author.objects.create(name='Peter Norvig', age=57)
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cls.a5 = Author.objects.create(name='Stuart Russell', age=46)
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p1 = Publisher.objects.create(name='Apress', num_awards=3)
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cls.b1 = Book.objects.create(
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isbn='159059725', pages=447, rating=4.5, price=Decimal('30.00'),
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contact=cls.a1, publisher=p1, pubdate=datetime.date(2007, 12, 6),
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name='The Definitive Guide to Django: Web Development Done Right',
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)
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cls.b2 = Book.objects.create(
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isbn='159059996', pages=300, rating=4.0, price=Decimal('29.69'),
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contact=cls.a3, publisher=p1, pubdate=datetime.date(2008, 6, 23),
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name='Practical Django Projects',
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)
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cls.b3 = Book.objects.create(
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isbn='013790395', pages=1132, rating=4.0, price=Decimal('82.80'),
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contact=cls.a4, publisher=p1, pubdate=datetime.date(1995, 1, 15),
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name='Artificial Intelligence: A Modern Approach',
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)
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cls.b4 = Book.objects.create(
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isbn='155860191', pages=946, rating=5.0, price=Decimal('75.00'),
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contact=cls.a4, publisher=p1, pubdate=datetime.date(1991, 10, 15),
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name='Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp',
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)
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cls.b1.authors.add(cls.a1, cls.a2)
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cls.b2.authors.add(cls.a3)
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cls.b3.authors.add(cls.a4, cls.a5)
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cls.b4.authors.add(cls.a4)
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Store.objects.create(
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name='Amazon.com',
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original_opening=datetime.datetime(1994, 4, 23, 9, 17, 42),
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friday_night_closing=datetime.time(23, 59, 59)
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)
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Store.objects.create(
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name='Books.com',
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original_opening=datetime.datetime(2001, 3, 15, 11, 23, 37),
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friday_night_closing=datetime.time(23, 59, 59)
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)
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def test_basic_alias(self):
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qs = Book.objects.alias(is_book=Value(1))
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self.assertIs(hasattr(qs.first(), 'is_book'), False)
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def test_basic_alias_annotation(self):
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qs = Book.objects.alias(
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is_book_alias=Value(1),
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).annotate(is_book=F('is_book_alias'))
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self.assertIs(hasattr(qs.first(), 'is_book_alias'), False)
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for book in qs:
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with self.subTest(book=book):
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self.assertEqual(book.is_book, 1)
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def test_basic_alias_f_annotation(self):
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qs = Book.objects.alias(
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another_rating_alias=F('rating')
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).annotate(another_rating=F('another_rating_alias'))
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self.assertIs(hasattr(qs.first(), 'another_rating_alias'), False)
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for book in qs:
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with self.subTest(book=book):
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self.assertEqual(book.another_rating, book.rating)
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def test_alias_after_annotation(self):
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qs = Book.objects.annotate(
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is_book=Value(1),
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).alias(is_book_alias=F('is_book'))
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book = qs.first()
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self.assertIs(hasattr(book, 'is_book'), True)
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self.assertIs(hasattr(book, 'is_book_alias'), False)
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def test_overwrite_annotation_with_alias(self):
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qs = Book.objects.annotate(is_book=Value(1)).alias(is_book=F('is_book'))
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self.assertIs(hasattr(qs.first(), 'is_book'), False)
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def test_overwrite_alias_with_annotation(self):
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qs = Book.objects.alias(is_book=Value(1)).annotate(is_book=F('is_book'))
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for book in qs:
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with self.subTest(book=book):
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self.assertEqual(book.is_book, 1)
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def test_alias_annotation_expression(self):
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qs = Book.objects.alias(
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is_book_alias=Value(1),
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).annotate(is_book=Coalesce('is_book_alias', 0))
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self.assertIs(hasattr(qs.first(), 'is_book_alias'), False)
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for book in qs:
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with self.subTest(book=book):
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self.assertEqual(book.is_book, 1)
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def test_alias_default_alias_expression(self):
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qs = Author.objects.alias(
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Sum('book__pages'),
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).filter(book__pages__sum__gt=2000)
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self.assertIs(hasattr(qs.first(), 'book__pages__sum'), False)
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self.assertSequenceEqual(qs, [self.a4])
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def test_joined_alias_annotation(self):
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qs = Book.objects.select_related('publisher').alias(
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num_awards_alias=F('publisher__num_awards'),
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).annotate(num_awards=F('num_awards_alias'))
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self.assertIs(hasattr(qs.first(), 'num_awards_alias'), False)
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for book in qs:
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with self.subTest(book=book):
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self.assertEqual(book.num_awards, book.publisher.num_awards)
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def test_alias_annotate_with_aggregation(self):
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qs = Book.objects.alias(
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is_book_alias=Value(1),
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rating_count_alias=Count('rating'),
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).annotate(
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is_book=F('is_book_alias'),
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rating_count=F('rating_count_alias'),
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)
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book = qs.first()
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self.assertIs(hasattr(book, 'is_book_alias'), False)
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self.assertIs(hasattr(book, 'rating_count_alias'), False)
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for book in qs:
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with self.subTest(book=book):
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self.assertEqual(book.is_book, 1)
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self.assertEqual(book.rating_count, 1)
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def test_filter_alias_with_f(self):
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qs = Book.objects.alias(
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other_rating=F('rating'),
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).filter(other_rating=4.5)
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self.assertIs(hasattr(qs.first(), 'other_rating'), False)
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self.assertSequenceEqual(qs, [self.b1])
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def test_filter_alias_with_double_f(self):
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qs = Book.objects.alias(
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other_rating=F('rating'),
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).filter(other_rating=F('rating'))
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self.assertIs(hasattr(qs.first(), 'other_rating'), False)
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self.assertEqual(qs.count(), Book.objects.count())
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def test_filter_alias_agg_with_double_f(self):
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qs = Book.objects.alias(
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sum_rating=Sum('rating'),
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).filter(sum_rating=F('sum_rating'))
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self.assertIs(hasattr(qs.first(), 'sum_rating'), False)
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self.assertEqual(qs.count(), Book.objects.count())
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def test_update_with_alias(self):
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Book.objects.alias(
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other_rating=F('rating') - 1,
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).update(rating=F('other_rating'))
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self.b1.refresh_from_db()
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self.assertEqual(self.b1.rating, 3.5)
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def test_order_by_alias(self):
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qs = Author.objects.alias(other_age=F('age')).order_by('other_age')
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self.assertIs(hasattr(qs.first(), 'other_age'), False)
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self.assertQuerysetEqual(qs, [34, 34, 35, 46, 57], lambda a: a.age)
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def test_order_by_alias_aggregate(self):
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qs = Author.objects.values('age').alias(age_count=Count('age')).order_by('age_count', 'age')
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self.assertIs(hasattr(qs.first(), 'age_count'), False)
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self.assertQuerysetEqual(qs, [35, 46, 57, 34], lambda a: a['age'])
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def test_dates_alias(self):
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qs = Book.objects.alias(
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pubdate_alias=F('pubdate'),
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).dates('pubdate_alias', 'month')
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self.assertCountEqual(qs, [
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datetime.date(1991, 10, 1),
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datetime.date(1995, 1, 1),
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datetime.date(2007, 12, 1),
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datetime.date(2008, 6, 1),
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])
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def test_datetimes_alias(self):
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qs = Store.objects.alias(
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original_opening_alias=F('original_opening'),
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).datetimes('original_opening_alias', 'year')
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self.assertCountEqual(qs, [
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datetime.datetime(1994, 1, 1),
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datetime.datetime(2001, 1, 1),
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])
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def test_aggregate_alias(self):
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msg = (
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"Cannot aggregate over the 'other_age' alias. Use annotate() to "
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"promote it."
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)
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with self.assertRaisesMessage(FieldError, msg):
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Author.objects.alias(
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other_age=F('age'),
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).aggregate(otherage_sum=Sum('other_age'))
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def test_defer_only_alias(self):
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qs = Book.objects.alias(rating_alias=F('rating') - 1)
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msg = "Book has no field named 'rating_alias'"
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for operation in ['defer', 'only']:
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with self.subTest(operation=operation):
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with self.assertRaisesMessage(FieldDoesNotExist, msg):
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getattr(qs, operation)('rating_alias').first()
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@skipUnlessDBFeature('can_distinct_on_fields')
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def test_distinct_on_alias(self):
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qs = Book.objects.alias(rating_alias=F('rating') - 1)
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msg = "Cannot resolve keyword 'rating_alias' into field."
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with self.assertRaisesMessage(FieldError, msg):
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qs.distinct('rating_alias').first()
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def test_values_alias(self):
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qs = Book.objects.alias(rating_alias=F('rating') - 1)
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msg = (
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"Cannot select the 'rating_alias' alias. Use annotate() to "
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"promote it."
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)
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for operation in ['values', 'values_list']:
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with self.subTest(operation=operation):
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with self.assertRaisesMessage(FieldError, msg):
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getattr(qs, operation)('rating_alias')
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