django/tests/aggregation/tests.py

import datetime
import re
from decimal import Decimal

from django.core.exceptions import FieldError
from django.db import connection
from django.db.models import (
    Avg, Count, DecimalField, DurationField, F, FloatField, Func, IntegerField,
    Max, Min, Sum, Value,
)
from django.db.models.expressions import Case, Exists, OuterRef, Subquery, When
from django.db.models.functions import Coalesce
from django.test import TestCase
from django.test.testcases import skipUnlessDBFeature
from django.test.utils import Approximate, CaptureQueriesContext
from django.utils import timezone

from .models import Author, Book, Publisher, Store


class AggregateTestCase(TestCase):

    @classmethod
    def setUpTestData(cls):
        cls.a1 = Author.objects.create(name='Adrian Holovaty', age=34)
        cls.a2 = Author.objects.create(name='Jacob Kaplan-Moss', age=35)
        cls.a3 = Author.objects.create(name='Brad Dayley', age=45)
        cls.a4 = Author.objects.create(name='James Bennett', age=29)
        cls.a5 = Author.objects.create(name='Jeffrey Forcier', age=37)
        cls.a6 = Author.objects.create(name='Paul Bissex', age=29)
        cls.a7 = Author.objects.create(name='Wesley J. Chun', age=25)
        cls.a8 = Author.objects.create(name='Peter Norvig', age=57)
        cls.a9 = Author.objects.create(name='Stuart Russell', age=46)
        cls.a1.friends.add(cls.a2, cls.a4)
        cls.a2.friends.add(cls.a1, cls.a7)
        cls.a4.friends.add(cls.a1)
        cls.a5.friends.add(cls.a6, cls.a7)
        cls.a6.friends.add(cls.a5, cls.a7)
        cls.a7.friends.add(cls.a2, cls.a5, cls.a6)
        cls.a8.friends.add(cls.a9)
        cls.a9.friends.add(cls.a8)

        cls.p1 = Publisher.objects.create(name='Apress', num_awards=3, duration=datetime.timedelta(days=1))
        cls.p2 = Publisher.objects.create(name='Sams', num_awards=1, duration=datetime.timedelta(days=2))
        cls.p3 = Publisher.objects.create(name='Prentice Hall', num_awards=7)
        cls.p4 = Publisher.objects.create(name='Morgan Kaufmann', num_awards=9)
        cls.p5 = Publisher.objects.create(name="Jonno's House of Books", num_awards=0)

        cls.b1 = Book.objects.create(
            isbn='159059725', name='The Definitive Guide to Django: Web Development Done Right',
            pages=447, rating=4.5, price=Decimal('30.00'), contact=cls.a1, publisher=cls.p1,
            pubdate=datetime.date(2007, 12, 6)
        )
        cls.b2 = Book.objects.create(
            isbn='067232959', name='Sams Teach Yourself Django in 24 Hours',
            pages=528, rating=3.0, price=Decimal('23.09'), contact=cls.a3, publisher=cls.p2,
            pubdate=datetime.date(2008, 3, 3)
        )
        cls.b3 = Book.objects.create(
            isbn='159059996', name='Practical Django Projects',
            pages=300, rating=4.0, price=Decimal('29.69'), contact=cls.a4, publisher=cls.p1,
            pubdate=datetime.date(2008, 6, 23)
        )
        cls.b4 = Book.objects.create(
            isbn='013235613', name='Python Web Development with Django',
            pages=350, rating=4.0, price=Decimal('29.69'), contact=cls.a5, publisher=cls.p3,
            pubdate=datetime.date(2008, 11, 3)
        )
        cls.b5 = Book.objects.create(
            isbn='013790395', name='Artificial Intelligence: A Modern Approach',
            pages=1132, rating=4.0, price=Decimal('82.80'), contact=cls.a8, publisher=cls.p3,
            pubdate=datetime.date(1995, 1, 15)
        )
        cls.b6 = Book.objects.create(
            isbn='155860191', name='Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp',
            pages=946, rating=5.0, price=Decimal('75.00'), contact=cls.a8, publisher=cls.p4,
            pubdate=datetime.date(1991, 10, 15)
        )
        cls.b1.authors.add(cls.a1, cls.a2)
        cls.b2.authors.add(cls.a3)
        cls.b3.authors.add(cls.a4)
        cls.b4.authors.add(cls.a5, cls.a6, cls.a7)
        cls.b5.authors.add(cls.a8, cls.a9)
        cls.b6.authors.add(cls.a8)

        s1 = Store.objects.create(
            name='Amazon.com',
            original_opening=datetime.datetime(1994, 4, 23, 9, 17, 42),
            friday_night_closing=datetime.time(23, 59, 59)
        )
        s2 = Store.objects.create(
            name='Books.com',
            original_opening=datetime.datetime(2001, 3, 15, 11, 23, 37),
            friday_night_closing=datetime.time(23, 59, 59)
        )
        s3 = Store.objects.create(
            name="Mamma and Pappa's Books",
            original_opening=datetime.datetime(1945, 4, 25, 16, 24, 14),
            friday_night_closing=datetime.time(21, 30)
        )
        s1.books.add(cls.b1, cls.b2, cls.b3, cls.b4, cls.b5, cls.b6)
        s2.books.add(cls.b1, cls.b3, cls.b5, cls.b6)
        s3.books.add(cls.b3, cls.b4, cls.b6)

    def test_empty_aggregate(self):
        self.assertEqual(Author.objects.all().aggregate(), {})

    def test_aggregate_in_order_by(self):
        msg = (
            'Using an aggregate in order_by() without also including it in '
            'annotate() is not allowed: Avg(F(book__rating)'
        )
        with self.assertRaisesMessage(FieldError, msg):
            Author.objects.values('age').order_by(Avg('book__rating'))

    def test_single_aggregate(self):
        vals = Author.objects.aggregate(Avg("age"))
        self.assertEqual(vals, {"age__avg": Approximate(37.4, places=1)})

    def test_multiple_aggregates(self):
        vals = Author.objects.aggregate(Sum("age"), Avg("age"))
        self.assertEqual(vals, {"age__sum": 337, "age__avg": Approximate(37.4, places=1)})

    def test_filter_aggregate(self):
        vals = Author.objects.filter(age__gt=29).aggregate(Sum("age"))
        self.assertEqual(vals, {'age__sum': 254})

    def test_related_aggregate(self):
        vals = Author.objects.aggregate(Avg("friends__age"))
        self.assertEqual(vals, {'friends__age__avg': Approximate(34.07, places=2)})

        vals = Book.objects.filter(rating__lt=4.5).aggregate(Avg("authors__age"))
        self.assertEqual(vals, {'authors__age__avg': Approximate(38.2857, places=2)})

        vals = Author.objects.all().filter(name__contains="a").aggregate(Avg("book__rating"))
        self.assertEqual(vals, {'book__rating__avg': 4.0})

        vals = Book.objects.aggregate(Sum("publisher__num_awards"))
        self.assertEqual(vals, {'publisher__num_awards__sum': 30})

        vals = Publisher.objects.aggregate(Sum("book__price"))
        self.assertEqual(vals, {'book__price__sum': Decimal('270.27')})

    def test_aggregate_multi_join(self):
        vals = Store.objects.aggregate(Max("books__authors__age"))
        self.assertEqual(vals, {'books__authors__age__max': 57})

        vals = Author.objects.aggregate(Min("book__publisher__num_awards"))
        self.assertEqual(vals, {'book__publisher__num_awards__min': 1})

    def test_aggregate_alias(self):
        vals = Store.objects.filter(name="Amazon.com").aggregate(amazon_mean=Avg("books__rating"))
        self.assertEqual(vals, {'amazon_mean': Approximate(4.08, places=2)})

    def test_annotate_basic(self):
        self.assertQuerysetEqual(
            Book.objects.annotate().order_by('pk'), [
                "The Definitive Guide to Django: Web Development Done Right",
                "Sams Teach Yourself Django in 24 Hours",
                "Practical Django Projects",
                "Python Web Development with Django",
                "Artificial Intelligence: A Modern Approach",
                "Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp"
            ],
            lambda b: b.name
        )

        books = Book.objects.annotate(mean_age=Avg("authors__age"))
        b = books.get(pk=self.b1.pk)
        self.assertEqual(
            b.name,
            'The Definitive Guide to Django: Web Development Done Right'
        )
        self.assertEqual(b.mean_age, 34.5)

    def test_annotate_defer(self):
        qs = Book.objects.annotate(
            page_sum=Sum("pages")).defer('name').filter(pk=self.b1.pk)

        rows = [
            (self.b1.id, "159059725", 447, "The Definitive Guide to Django: Web Development Done Right")
        ]
        self.assertQuerysetEqual(
            qs.order_by('pk'), rows,
            lambda r: (r.id, r.isbn, r.page_sum, r.name)
        )

    def test_annotate_defer_select_related(self):
        qs = Book.objects.select_related('contact').annotate(
            page_sum=Sum("pages")).defer('name').filter(pk=self.b1.pk)

        rows = [
            (self.b1.id, "159059725", 447, "Adrian Holovaty",
             "The Definitive Guide to Django: Web Development Done Right")
        ]
        self.assertQuerysetEqual(
            qs.order_by('pk'), rows,
            lambda r: (r.id, r.isbn, r.page_sum, r.contact.name, r.name)
        )

    def test_annotate_m2m(self):
        books = Book.objects.filter(rating__lt=4.5).annotate(Avg("authors__age")).order_by("name")
        self.assertQuerysetEqual(
            books, [
                ('Artificial Intelligence: A Modern Approach', 51.5),
                ('Practical Django Projects', 29.0),
                ('Python Web Development with Django', Approximate(30.3, places=1)),
                ('Sams Teach Yourself Django in 24 Hours', 45.0)
            ],
            lambda b: (b.name, b.authors__age__avg),
        )

        books = Book.objects.annotate(num_authors=Count("authors")).order_by("name")
        self.assertQuerysetEqual(
            books, [
                ('Artificial Intelligence: A Modern Approach', 2),
                ('Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp', 1),
                ('Practical Django Projects', 1),
                ('Python Web Development with Django', 3),
                ('Sams Teach Yourself Django in 24 Hours', 1),
                ('The Definitive Guide to Django: Web Development Done Right', 2)
            ],
            lambda b: (b.name, b.num_authors)
        )

    def test_backwards_m2m_annotate(self):
        authors = Author.objects.filter(name__contains="a").annotate(Avg("book__rating")).order_by("name")
        self.assertQuerysetEqual(
            authors, [
                ('Adrian Holovaty', 4.5),
                ('Brad Dayley', 3.0),
                ('Jacob Kaplan-Moss', 4.5),
                ('James Bennett', 4.0),
                ('Paul Bissex', 4.0),
                ('Stuart Russell', 4.0)
            ],
            lambda a: (a.name, a.book__rating__avg)
        )

        authors = Author.objects.annotate(num_books=Count("book")).order_by("name")
        self.assertQuerysetEqual(
            authors, [
                ('Adrian Holovaty', 1),
                ('Brad Dayley', 1),
                ('Jacob Kaplan-Moss', 1),
                ('James Bennett', 1),
                ('Jeffrey Forcier', 1),
                ('Paul Bissex', 1),
                ('Peter Norvig', 2),
                ('Stuart Russell', 1),
                ('Wesley J. Chun', 1)
            ],
            lambda a: (a.name, a.num_books)
        )

    def test_reverse_fkey_annotate(self):
        books = Book.objects.annotate(Sum("publisher__num_awards")).order_by("name")
        self.assertQuerysetEqual(
            books, [
                ('Artificial Intelligence: A Modern Approach', 7),
                ('Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp', 9),
                ('Practical Django Projects', 3),
                ('Python Web Development with Django', 7),
                ('Sams Teach Yourself Django in 24 Hours', 1),
                ('The Definitive Guide to Django: Web Development Done Right', 3)
            ],
            lambda b: (b.name, b.publisher__num_awards__sum)
        )

        publishers = Publisher.objects.annotate(Sum("book__price")).order_by("name")
        self.assertQuerysetEqual(
            publishers, [
                ('Apress', Decimal("59.69")),
                ("Jonno's House of Books", None),
                ('Morgan Kaufmann', Decimal("75.00")),
                ('Prentice Hall', Decimal("112.49")),
                ('Sams', Decimal("23.09"))
            ],
            lambda p: (p.name, p.book__price__sum)
        )

    def test_annotate_values(self):
        books = list(Book.objects.filter(pk=self.b1.pk).annotate(mean_age=Avg("authors__age")).values())
        self.assertEqual(
            books, [
                {
                    "contact_id": self.a1.id,
                    "id": self.b1.id,
                    "isbn": "159059725",
                    "mean_age": 34.5,
                    "name": "The Definitive Guide to Django: Web Development Done Right",
                    "pages": 447,
                    "price": Approximate(Decimal("30")),
                    "pubdate": datetime.date(2007, 12, 6),
                    "publisher_id": self.p1.id,
                    "rating": 4.5,
                }
            ]
        )

        books = (
            Book.objects
            .filter(pk=self.b1.pk)
            .annotate(mean_age=Avg('authors__age'))
            .values('pk', 'isbn', 'mean_age')
        )
        self.assertEqual(
            list(books), [
                {
                    "pk": self.b1.pk,
                    "isbn": "159059725",
                    "mean_age": 34.5,
                }
            ]
        )

        books = Book.objects.filter(pk=self.b1.pk).annotate(mean_age=Avg("authors__age")).values("name")
        self.assertEqual(
            list(books),
            [{'name': 'The Definitive Guide to Django: Web Development Done Right'}],
        )

        books = Book.objects.filter(pk=self.b1.pk).values().annotate(mean_age=Avg('authors__age'))
        self.assertEqual(
            list(books), [
                {
                    "contact_id": self.a1.id,
                    "id": self.b1.id,
                    "isbn": "159059725",
                    "mean_age": 34.5,
                    "name": "The Definitive Guide to Django: Web Development Done Right",
                    "pages": 447,
                    "price": Approximate(Decimal("30")),
                    "pubdate": datetime.date(2007, 12, 6),
                    "publisher_id": self.p1.id,
                    "rating": 4.5,
                }
            ]
        )

        books = (
            Book.objects
            .values("rating")
            .annotate(n_authors=Count("authors__id"), mean_age=Avg("authors__age"))
            .order_by("rating")
        )
        self.assertEqual(
            list(books), [
                {
                    "rating": 3.0,
                    "n_authors": 1,
                    "mean_age": 45.0,
                },
                {
                    "rating": 4.0,
                    "n_authors": 6,
                    "mean_age": Approximate(37.16, places=1)
                },
                {
                    "rating": 4.5,
                    "n_authors": 2,
                    "mean_age": 34.5,
                },
                {
                    "rating": 5.0,
                    "n_authors": 1,
                    "mean_age": 57.0,
                }
            ]
        )

        authors = Author.objects.annotate(Avg("friends__age")).order_by("name")
        self.assertQuerysetEqual(
            authors, [
                ('Adrian Holovaty', 32.0),
                ('Brad Dayley', None),
                ('Jacob Kaplan-Moss', 29.5),
                ('James Bennett', 34.0),
                ('Jeffrey Forcier', 27.0),
                ('Paul Bissex', 31.0),
                ('Peter Norvig', 46.0),
                ('Stuart Russell', 57.0),
                ('Wesley J. Chun', Approximate(33.66, places=1))
            ],
            lambda a: (a.name, a.friends__age__avg)
        )

    def test_count(self):
        vals = Book.objects.aggregate(Count("rating"))
        self.assertEqual(vals, {"rating__count": 6})

    def test_count_star(self):
        with self.assertNumQueries(1) as ctx:
            Book.objects.aggregate(n=Count("*"))
        sql = ctx.captured_queries[0]['sql']
        self.assertIn('SELECT COUNT(*) ', sql)

    def test_count_distinct_expression(self):
        aggs = Book.objects.aggregate(
            distinct_ratings=Count(Case(When(pages__gt=300, then='rating')), distinct=True),
        )
        self.assertEqual(aggs['distinct_ratings'], 4)

    def test_distinct_on_aggregate(self):
        for aggregate, expected_result in (
            (Avg, 4.125),
            (Count, 4),
            (Sum, 16.5),
        ):
            with self.subTest(aggregate=aggregate.__name__):
                books = Book.objects.aggregate(ratings=aggregate('rating', distinct=True))
                self.assertEqual(books['ratings'], expected_result)

    def test_non_grouped_annotation_not_in_group_by(self):
        """
        An annotation not included in values() before an aggregate should be
        excluded from the group by clause.
        """
        qs = (
            Book.objects.annotate(xprice=F('price')).filter(rating=4.0).values('rating')
                .annotate(count=Count('publisher_id', distinct=True)).values('count', 'rating').order_by('count')
        )
        self.assertEqual(list(qs), [{'rating': 4.0, 'count': 2}])

    def test_grouped_annotation_in_group_by(self):
        """
        An annotation included in values() before an aggregate should be
        included in the group by clause.
        """
        qs = (
            Book.objects.annotate(xprice=F('price')).filter(rating=4.0).values('rating', 'xprice')
                .annotate(count=Count('publisher_id', distinct=True)).values('count', 'rating').order_by('count')
        )
        self.assertEqual(
            list(qs), [
                {'rating': 4.0, 'count': 1},
                {'rating': 4.0, 'count': 2},
            ]
        )

    def test_fkey_aggregate(self):
        explicit = list(Author.objects.annotate(Count('book__id')))
        implicit = list(Author.objects.annotate(Count('book')))
        self.assertCountEqual(explicit, implicit)

    def test_annotate_ordering(self):
        books = Book.objects.values('rating').annotate(oldest=Max('authors__age')).order_by('oldest', 'rating')
        self.assertEqual(
            list(books), [
                {'rating': 4.5, 'oldest': 35},
                {'rating': 3.0, 'oldest': 45},
                {'rating': 4.0, 'oldest': 57},
                {'rating': 5.0, 'oldest': 57},
            ]
        )

        books = Book.objects.values("rating").annotate(oldest=Max("authors__age")).order_by("-oldest", "-rating")
        self.assertEqual(
            list(books), [
                {'rating': 5.0, 'oldest': 57},
                {'rating': 4.0, 'oldest': 57},
                {'rating': 3.0, 'oldest': 45},
                {'rating': 4.5, 'oldest': 35},
            ]
        )

    def test_aggregate_annotation(self):
        vals = Book.objects.annotate(num_authors=Count("authors__id")).aggregate(Avg("num_authors"))
        self.assertEqual(vals, {"num_authors__avg": Approximate(1.66, places=1)})

    def test_avg_duration_field(self):
        # Explicit `output_field`.
        self.assertEqual(
            Publisher.objects.aggregate(Avg('duration', output_field=DurationField())),
            {'duration__avg': datetime.timedelta(days=1, hours=12)}
        )
        # Implicit `output_field`.
        self.assertEqual(
            Publisher.objects.aggregate(Avg('duration')),
            {'duration__avg': datetime.timedelta(days=1, hours=12)}
        )

    def test_sum_duration_field(self):
        self.assertEqual(
            Publisher.objects.aggregate(Sum('duration', output_field=DurationField())),
            {'duration__sum': datetime.timedelta(days=3)}
        )

    def test_sum_distinct_aggregate(self):
        """
        Sum on a distinct() QuerySet should aggregate only the distinct items.
        """
        authors = Author.objects.filter(book__in=[self.b5, self.b6])
        self.assertEqual(authors.count(), 3)

        distinct_authors = authors.distinct()
        self.assertEqual(distinct_authors.count(), 2)

        # Selected author ages are 57 and 46
        age_sum = distinct_authors.aggregate(Sum('age'))
        self.assertEqual(age_sum['age__sum'], 103)

    def test_filtering(self):
        p = Publisher.objects.create(name='Expensive Publisher', num_awards=0)
        Book.objects.create(
            name='ExpensiveBook1',
            pages=1,
            isbn='111',
            rating=3.5,
            price=Decimal("1000"),
            publisher=p,
            contact_id=self.a1.id,
            pubdate=datetime.date(2008, 12, 1)
        )
        Book.objects.create(
            name='ExpensiveBook2',
            pages=1,
            isbn='222',
            rating=4.0,
            price=Decimal("1000"),
            publisher=p,
            contact_id=self.a1.id,
            pubdate=datetime.date(2008, 12, 2)
        )
        Book.objects.create(
            name='ExpensiveBook3',
            pages=1,
            isbn='333',
            rating=4.5,
            price=Decimal("35"),
            publisher=p,
            contact_id=self.a1.id,
            pubdate=datetime.date(2008, 12, 3)
        )

        publishers = Publisher.objects.annotate(num_books=Count("book__id")).filter(num_books__gt=1).order_by("pk")
        self.assertQuerysetEqual(
            publishers,
            ['Apress', 'Prentice Hall', 'Expensive Publisher'],
            lambda p: p.name,
        )

        publishers = Publisher.objects.filter(book__price__lt=Decimal("40.0")).order_by("pk")
        self.assertQuerysetEqual(
            publishers, [
                "Apress",
                "Apress",
                "Sams",
                "Prentice Hall",
                "Expensive Publisher",
            ],
            lambda p: p.name
        )

        publishers = (
            Publisher.objects
            .annotate(num_books=Count("book__id"))
            .filter(num_books__gt=1, book__price__lt=Decimal("40.0"))
            .order_by("pk")
        )
        self.assertQuerysetEqual(
            publishers,
            ['Apress', 'Prentice Hall', 'Expensive Publisher'],
            lambda p: p.name,
        )

        publishers = (
            Publisher.objects
            .filter(book__price__lt=Decimal("40.0"))
            .annotate(num_books=Count("book__id"))
            .filter(num_books__gt=1)
            .order_by("pk")
        )
        self.assertQuerysetEqual(publishers, ['Apress'], lambda p: p.name)

        publishers = Publisher.objects.annotate(num_books=Count("book")).filter(num_books__range=[1, 3]).order_by("pk")
        self.assertQuerysetEqual(
            publishers, [
                "Apress",
                "Sams",
                "Prentice Hall",
                "Morgan Kaufmann",
                "Expensive Publisher",
            ],
            lambda p: p.name
        )

        publishers = Publisher.objects.annotate(num_books=Count("book")).filter(num_books__range=[1, 2]).order_by("pk")
        self.assertQuerysetEqual(
            publishers,
            ['Apress', 'Sams', 'Prentice Hall', 'Morgan Kaufmann'],
            lambda p: p.name
        )

        publishers = Publisher.objects.annotate(num_books=Count("book")).filter(num_books__in=[1, 3]).order_by("pk")
        self.assertQuerysetEqual(
            publishers,
            ['Sams', 'Morgan Kaufmann', 'Expensive Publisher'],
            lambda p: p.name,
        )

        publishers = Publisher.objects.annotate(num_books=Count("book")).filter(num_books__isnull=True)
        self.assertEqual(len(publishers), 0)

    def test_annotation(self):
        vals = Author.objects.filter(pk=self.a1.pk).aggregate(Count("friends__id"))
        self.assertEqual(vals, {"friends__id__count": 2})

        books = Book.objects.annotate(num_authors=Count("authors__name")).filter(num_authors__exact=2).order_by("pk")
        self.assertQuerysetEqual(
            books, [
                "The Definitive Guide to Django: Web Development Done Right",
                "Artificial Intelligence: A Modern Approach",
            ],
            lambda b: b.name
        )

        authors = (
            Author.objects
            .annotate(num_friends=Count("friends__id", distinct=True))
            .filter(num_friends=0)
            .order_by("pk")
        )
        self.assertQuerysetEqual(authors, ['Brad Dayley'], lambda a: a.name)

        publishers = Publisher.objects.annotate(num_books=Count("book__id")).filter(num_books__gt=1).order_by("pk")
        self.assertQuerysetEqual(publishers, ['Apress', 'Prentice Hall'], lambda p: p.name)

        publishers = (
            Publisher.objects
            .filter(book__price__lt=Decimal("40.0"))
            .annotate(num_books=Count("book__id"))
            .filter(num_books__gt=1)
        )
        self.assertQuerysetEqual(publishers, ['Apress'], lambda p: p.name)

        books = (
            Book.objects
            .annotate(num_authors=Count("authors__id"))
            .filter(authors__name__contains="Norvig", num_authors__gt=1)
        )
        self.assertQuerysetEqual(
            books,
            ['Artificial Intelligence: A Modern Approach'],
            lambda b: b.name
        )

    def test_more_aggregation(self):
        a = Author.objects.get(name__contains='Norvig')
        b = Book.objects.get(name__contains='Done Right')
        b.authors.add(a)
        b.save()

        vals = (
            Book.objects
            .annotate(num_authors=Count("authors__id"))
            .filter(authors__name__contains="Norvig", num_authors__gt=1)
            .aggregate(Avg("rating"))
        )
        self.assertEqual(vals, {"rating__avg": 4.25})

    def test_even_more_aggregate(self):
        publishers = Publisher.objects.annotate(
            earliest_book=Min("book__pubdate"),
        ).exclude(earliest_book=None).order_by("earliest_book").values(
            'earliest_book',
            'num_awards',
            'id',
            'name',
        )
        self.assertEqual(
            list(publishers), [
                {
                    'earliest_book': datetime.date(1991, 10, 15),
                    'num_awards': 9,
                    'id': self.p4.id,
                    'name': 'Morgan Kaufmann'
                },
                {
                    'earliest_book': datetime.date(1995, 1, 15),
                    'num_awards': 7,
                    'id': self.p3.id,
                    'name': 'Prentice Hall'
                },
                {
                    'earliest_book': datetime.date(2007, 12, 6),
                    'num_awards': 3,
                    'id': self.p1.id,
                    'name': 'Apress'
                },
                {
                    'earliest_book': datetime.date(2008, 3, 3),
                    'num_awards': 1,
                    'id': self.p2.id,
                    'name': 'Sams'
                }
            ]
        )

        vals = Store.objects.aggregate(Max("friday_night_closing"), Min("original_opening"))
        self.assertEqual(
            vals,
            {
                "friday_night_closing__max": datetime.time(23, 59, 59),
                "original_opening__min": datetime.datetime(1945, 4, 25, 16, 24, 14),
            }
        )

    def test_annotate_values_list(self):
        books = (
            Book.objects
            .filter(pk=self.b1.pk)
            .annotate(mean_age=Avg("authors__age"))
            .values_list("pk", "isbn", "mean_age")
        )
        self.assertEqual(list(books), [(self.b1.id, '159059725', 34.5)])

        books = Book.objects.filter(pk=self.b1.pk).annotate(mean_age=Avg("authors__age")).values_list("isbn")
        self.assertEqual(list(books), [('159059725',)])

        books = Book.objects.filter(pk=self.b1.pk).annotate(mean_age=Avg("authors__age")).values_list("mean_age")
        self.assertEqual(list(books), [(34.5,)])

        books = (
            Book.objects
            .filter(pk=self.b1.pk)
            .annotate(mean_age=Avg("authors__age"))
            .values_list("mean_age", flat=True)
        )
        self.assertEqual(list(books), [34.5])

        books = Book.objects.values_list("price").annotate(count=Count("price")).order_by("-count", "price")
        self.assertEqual(
            list(books), [
                (Decimal("29.69"), 2),
                (Decimal('23.09'), 1),
                (Decimal('30'), 1),
                (Decimal('75'), 1),
                (Decimal('82.8'), 1),
            ]
        )

    def test_dates_with_aggregation(self):
        """
        .dates() returns a distinct set of dates when applied to a
        QuerySet with aggregation.

        Refs #18056. Previously, .dates() would return distinct (date_kind,
        aggregation) sets, in this case (year, num_authors), so 2008 would be
        returned twice because there are books from 2008 with a different
        number of authors.
        """
        dates = Book.objects.annotate(num_authors=Count("authors")).dates('pubdate', 'year')
        self.assertQuerysetEqual(
            dates, [
                "datetime.date(1991, 1, 1)",
                "datetime.date(1995, 1, 1)",
                "datetime.date(2007, 1, 1)",
                "datetime.date(2008, 1, 1)"
            ]
        )

    def test_values_aggregation(self):
        # Refs #20782
        max_rating = Book.objects.values('rating').aggregate(max_rating=Max('rating'))
        self.assertEqual(max_rating['max_rating'], 5)
        max_books_per_rating = Book.objects.values('rating').annotate(
            books_per_rating=Count('id')
        ).aggregate(Max('books_per_rating'))
        self.assertEqual(
            max_books_per_rating,
            {'books_per_rating__max': 3})

    def test_ticket17424(self):
        """
        Doing exclude() on a foreign model after annotate() doesn't crash.
        """
        all_books = list(Book.objects.values_list('pk', flat=True).order_by('pk'))
        annotated_books = Book.objects.order_by('pk').annotate(one=Count("id"))

        # The value doesn't matter, we just need any negative
        # constraint on a related model that's a noop.
        excluded_books = annotated_books.exclude(publisher__name="__UNLIKELY_VALUE__")

        # Try to generate query tree
        str(excluded_books.query)

        self.assertQuerysetEqual(excluded_books, all_books, lambda x: x.pk)

        # Check internal state
        self.assertIsNone(annotated_books.query.alias_map["aggregation_book"].join_type)
        self.assertIsNone(excluded_books.query.alias_map["aggregation_book"].join_type)

    def test_ticket12886(self):
        """
        Aggregation over sliced queryset works correctly.
        """
        qs = Book.objects.all().order_by('-rating')[0:3]
        vals = qs.aggregate(average_top3_rating=Avg('rating'))['average_top3_rating']
        self.assertAlmostEqual(vals, 4.5, places=2)

    def test_ticket11881(self):
        """
        Subqueries do not needlessly contain ORDER BY, SELECT FOR UPDATE or
        select_related() stuff.
        """
        qs = Book.objects.all().select_for_update().order_by(
            'pk').select_related('publisher').annotate(max_pk=Max('pk'))
        with CaptureQueriesContext(connection) as captured_queries:
            qs.aggregate(avg_pk=Avg('max_pk'))
            self.assertEqual(len(captured_queries), 1)
            qstr = captured_queries[0]['sql'].lower()
            self.assertNotIn('for update', qstr)
            forced_ordering = connection.ops.force_no_ordering()
            if forced_ordering:
                # If the backend needs to force an ordering we make sure it's
                # the only "ORDER BY" clause present in the query.
                self.assertEqual(
                    re.findall(r'order by (\w+)', qstr),
                    [', '.join(f[1][0] for f in forced_ordering).lower()]
                )
            else:
                self.assertNotIn('order by', qstr)
            self.assertEqual(qstr.count(' join '), 0)

    def test_decimal_max_digits_has_no_effect(self):
        Book.objects.all().delete()
        a1 = Author.objects.first()
        p1 = Publisher.objects.first()
        thedate = timezone.now()
        for i in range(10):
            Book.objects.create(
                isbn="abcde{}".format(i), name="none", pages=10, rating=4.0,
                price=9999.98, contact=a1, publisher=p1, pubdate=thedate)

        book = Book.objects.aggregate(price_sum=Sum('price'))
        self.assertEqual(book['price_sum'], Decimal("99999.80"))

    def test_nonaggregate_aggregation_throws(self):
        with self.assertRaisesMessage(TypeError, 'fail is not an aggregate expression'):
            Book.objects.aggregate(fail=F('price'))

    def test_nonfield_annotation(self):
        book = Book.objects.annotate(val=Max(Value(2, output_field=IntegerField()))).first()
        self.assertEqual(book.val, 2)
        book = Book.objects.annotate(val=Max(Value(2), output_field=IntegerField())).first()
        self.assertEqual(book.val, 2)
        book = Book.objects.annotate(val=Max(2, output_field=IntegerField())).first()
        self.assertEqual(book.val, 2)

    def test_missing_output_field_raises_error(self):
        with self.assertRaisesMessage(FieldError, 'Cannot resolve expression type, unknown output_field'):
            Book.objects.annotate(val=Max(2)).first()

    def test_annotation_expressions(self):
        authors = Author.objects.annotate(combined_ages=Sum(F('age') + F('friends__age'))).order_by('name')
        authors2 = Author.objects.annotate(combined_ages=Sum('age') + Sum('friends__age')).order_by('name')
        for qs in (authors, authors2):
            self.assertQuerysetEqual(
                qs, [
                    ('Adrian Holovaty', 132),
                    ('Brad Dayley', None),
                    ('Jacob Kaplan-Moss', 129),
                    ('James Bennett', 63),
                    ('Jeffrey Forcier', 128),
                    ('Paul Bissex', 120),
                    ('Peter Norvig', 103),
                    ('Stuart Russell', 103),
                    ('Wesley J. Chun', 176)
                ],
                lambda a: (a.name, a.combined_ages)
            )

    def test_aggregation_expressions(self):
        a1 = Author.objects.aggregate(av_age=Sum('age') / Count('*'))
        a2 = Author.objects.aggregate(av_age=Sum('age') / Count('age'))
        a3 = Author.objects.aggregate(av_age=Avg('age'))
        self.assertEqual(a1, {'av_age': 37})
        self.assertEqual(a2, {'av_age': 37})
        self.assertEqual(a3, {'av_age': Approximate(37.4, places=1)})

    def test_avg_decimal_field(self):
        v = Book.objects.filter(rating=4).aggregate(avg_price=(Avg('price')))['avg_price']
        self.assertIsInstance(v, Decimal)
        self.assertEqual(v, Approximate(Decimal('47.39'), places=2))

    def test_order_of_precedence(self):
        p1 = Book.objects.filter(rating=4).aggregate(avg_price=(Avg('price') + 2) * 3)
        self.assertEqual(p1, {'avg_price': Approximate(Decimal('148.18'), places=2)})

        p2 = Book.objects.filter(rating=4).aggregate(avg_price=Avg('price') + 2 * 3)
        self.assertEqual(p2, {'avg_price': Approximate(Decimal('53.39'), places=2)})

    def test_combine_different_types(self):
        msg = (
            'Expression contains mixed types: FloatField, IntegerField. '
            'You must set output_field.'
        )
        qs = Book.objects.annotate(sums=Sum('rating') + Sum('pages') + Sum('price'))
        with self.assertRaisesMessage(FieldError, msg):
            qs.first()
        with self.assertRaisesMessage(FieldError, msg):
            qs.first()

        b1 = Book.objects.annotate(sums=Sum(F('rating') + F('pages') + F('price'),
                                   output_field=IntegerField())).get(pk=self.b4.pk)
        self.assertEqual(b1.sums, 383)

        b2 = Book.objects.annotate(sums=Sum(F('rating') + F('pages') + F('price'),
                                   output_field=FloatField())).get(pk=self.b4.pk)
        self.assertEqual(b2.sums, 383.69)

        b3 = Book.objects.annotate(sums=Sum(F('rating') + F('pages') + F('price'),
                                   output_field=DecimalField())).get(pk=self.b4.pk)
        self.assertEqual(b3.sums, Approximate(Decimal("383.69"), places=2))

    def test_complex_aggregations_require_kwarg(self):
        with self.assertRaisesMessage(TypeError, 'Complex annotations require an alias'):
            Author.objects.annotate(Sum(F('age') + F('friends__age')))
        with self.assertRaisesMessage(TypeError, 'Complex aggregates require an alias'):
            Author.objects.aggregate(Sum('age') / Count('age'))
        with self.assertRaisesMessage(TypeError, 'Complex aggregates require an alias'):
            Author.objects.aggregate(Sum(1))

    def test_aggregate_over_complex_annotation(self):
        qs = Author.objects.annotate(
            combined_ages=Sum(F('age') + F('friends__age')))

        age = qs.aggregate(max_combined_age=Max('combined_ages'))
        self.assertEqual(age['max_combined_age'], 176)

        age = qs.aggregate(max_combined_age_doubled=Max('combined_ages') * 2)
        self.assertEqual(age['max_combined_age_doubled'], 176 * 2)

        age = qs.aggregate(
            max_combined_age_doubled=Max('combined_ages') + Max('combined_ages'))
        self.assertEqual(age['max_combined_age_doubled'], 176 * 2)

        age = qs.aggregate(
            max_combined_age_doubled=Max('combined_ages') + Max('combined_ages'),
            sum_combined_age=Sum('combined_ages'))
        self.assertEqual(age['max_combined_age_doubled'], 176 * 2)
        self.assertEqual(age['sum_combined_age'], 954)

        age = qs.aggregate(
            max_combined_age_doubled=Max('combined_ages') + Max('combined_ages'),
            sum_combined_age_doubled=Sum('combined_ages') + Sum('combined_ages'))
        self.assertEqual(age['max_combined_age_doubled'], 176 * 2)
        self.assertEqual(age['sum_combined_age_doubled'], 954 * 2)

    def test_values_annotation_with_expression(self):
        # ensure the F() is promoted to the group by clause
        qs = Author.objects.values('name').annotate(another_age=Sum('age') + F('age'))
        a = qs.get(name="Adrian Holovaty")
        self.assertEqual(a['another_age'], 68)

        qs = qs.annotate(friend_count=Count('friends'))
        a = qs.get(name="Adrian Holovaty")
        self.assertEqual(a['friend_count'], 2)

        qs = qs.annotate(combined_age=Sum('age') + F('friends__age')).filter(
            name="Adrian Holovaty").order_by('-combined_age')
        self.assertEqual(
            list(qs), [
                {
                    "name": 'Adrian Holovaty',
                    "another_age": 68,
                    "friend_count": 1,
                    "combined_age": 69
                },
                {
                    "name": 'Adrian Holovaty',
                    "another_age": 68,
                    "friend_count": 1,
                    "combined_age": 63
                }
            ]
        )

        vals = qs.values('name', 'combined_age')
        self.assertEqual(
            list(vals), [
                {'name': 'Adrian Holovaty', 'combined_age': 69},
                {'name': 'Adrian Holovaty', 'combined_age': 63},
            ]
        )

    def test_annotate_values_aggregate(self):
        alias_age = Author.objects.annotate(
            age_alias=F('age')
        ).values(
            'age_alias',
        ).aggregate(sum_age=Sum('age_alias'))

        age = Author.objects.values('age').aggregate(sum_age=Sum('age'))

        self.assertEqual(alias_age['sum_age'], age['sum_age'])

    def test_annotate_over_annotate(self):
        author = Author.objects.annotate(
            age_alias=F('age')
        ).annotate(
            sum_age=Sum('age_alias')
        ).get(name="Adrian Holovaty")

        other_author = Author.objects.annotate(
            sum_age=Sum('age')
        ).get(name="Adrian Holovaty")

        self.assertEqual(author.sum_age, other_author.sum_age)

    def test_annotated_aggregate_over_annotated_aggregate(self):
        with self.assertRaisesMessage(FieldError, "Cannot compute Sum('id__max'): 'id__max' is an aggregate"):
            Book.objects.annotate(Max('id')).annotate(Sum('id__max'))

        class MyMax(Max):
            def as_sql(self, compiler, connection):
                self.set_source_expressions(self.get_source_expressions()[0:1])
                return super().as_sql(compiler, connection)

        with self.assertRaisesMessage(FieldError, "Cannot compute Max('id__max'): 'id__max' is an aggregate"):
            Book.objects.annotate(Max('id')).annotate(my_max=MyMax('id__max', 'price'))

    def test_multi_arg_aggregate(self):
        class MyMax(Max):
            output_field = DecimalField()

            def as_sql(self, compiler, connection):
                copy = self.copy()
                copy.set_source_expressions(copy.get_source_expressions()[0:1])
                return super(MyMax, copy).as_sql(compiler, connection)

        with self.assertRaisesMessage(TypeError, 'Complex aggregates require an alias'):
            Book.objects.aggregate(MyMax('pages', 'price'))

        with self.assertRaisesMessage(TypeError, 'Complex annotations require an alias'):
            Book.objects.annotate(MyMax('pages', 'price'))

        Book.objects.aggregate(max_field=MyMax('pages', 'price'))

    def test_add_implementation(self):
        class MySum(Sum):
            pass

        # test completely changing how the output is rendered
        def lower_case_function_override(self, compiler, connection):
            sql, params = compiler.compile(self.source_expressions[0])
            substitutions = {'function': self.function.lower(), 'expressions': sql, 'distinct': ''}
            substitutions.update(self.extra)
            return self.template % substitutions, params
        setattr(MySum, 'as_' + connection.vendor, lower_case_function_override)

        qs = Book.objects.annotate(
            sums=MySum(F('rating') + F('pages') + F('price'), output_field=IntegerField())
        )
        self.assertEqual(str(qs.query).count('sum('), 1)
        b1 = qs.get(pk=self.b4.pk)
        self.assertEqual(b1.sums, 383)

        # test changing the dict and delegating
        def lower_case_function_super(self, compiler, connection):
            self.extra['function'] = self.function.lower()
            return super(MySum, self).as_sql(compiler, connection)
        setattr(MySum, 'as_' + connection.vendor, lower_case_function_super)

        qs = Book.objects.annotate(
            sums=MySum(F('rating') + F('pages') + F('price'), output_field=IntegerField())
        )
        self.assertEqual(str(qs.query).count('sum('), 1)
        b1 = qs.get(pk=self.b4.pk)
        self.assertEqual(b1.sums, 383)

        # test overriding all parts of the template
        def be_evil(self, compiler, connection):
            substitutions = {'function': 'MAX', 'expressions': '2', 'distinct': ''}
            substitutions.update(self.extra)
            return self.template % substitutions, ()
        setattr(MySum, 'as_' + connection.vendor, be_evil)

        qs = Book.objects.annotate(
            sums=MySum(F('rating') + F('pages') + F('price'), output_field=IntegerField())
        )
        self.assertEqual(str(qs.query).count('MAX('), 1)
        b1 = qs.get(pk=self.b4.pk)
        self.assertEqual(b1.sums, 2)

    def test_complex_values_aggregation(self):
        max_rating = Book.objects.values('rating').aggregate(
            double_max_rating=Max('rating') + Max('rating'))
        self.assertEqual(max_rating['double_max_rating'], 5 * 2)

        max_books_per_rating = Book.objects.values('rating').annotate(
            books_per_rating=Count('id') + 5
        ).aggregate(Max('books_per_rating'))
        self.assertEqual(
            max_books_per_rating,
            {'books_per_rating__max': 3 + 5})

    def test_expression_on_aggregation(self):

        # Create a plain expression
        class Greatest(Func):
            function = 'GREATEST'

            def as_sqlite(self, compiler, connection, **extra_context):
                return super().as_sql(compiler, connection, function='MAX', **extra_context)

        qs = Publisher.objects.annotate(
            price_or_median=Greatest(Avg('book__rating', output_field=DecimalField()), Avg('book__price'))
        ).filter(price_or_median__gte=F('num_awards')).order_by('num_awards')
        self.assertQuerysetEqual(
            qs, [1, 3, 7, 9], lambda v: v.num_awards)

        qs2 = Publisher.objects.annotate(
            rating_or_num_awards=Greatest(Avg('book__rating'), F('num_awards'),
                                          output_field=FloatField())
        ).filter(rating_or_num_awards__gt=F('num_awards')).order_by('num_awards')
        self.assertQuerysetEqual(
            qs2, [1, 3], lambda v: v.num_awards)

    def test_arguments_must_be_expressions(self):
        msg = 'QuerySet.aggregate() received non-expression(s): %s.'
        with self.assertRaisesMessage(TypeError, msg % FloatField()):
            Book.objects.aggregate(FloatField())
        with self.assertRaisesMessage(TypeError, msg % True):
            Book.objects.aggregate(is_book=True)
        with self.assertRaisesMessage(TypeError, msg % ', '.join([str(FloatField()), 'True'])):
            Book.objects.aggregate(FloatField(), Avg('price'), is_book=True)

    def test_aggregation_subquery_annotation(self):
        """Subquery annotations are excluded from the GROUP BY if they are
        not explicitly grouped against."""
        latest_book_pubdate_qs = Book.objects.filter(
            publisher=OuterRef('pk')
        ).order_by('-pubdate').values('pubdate')[:1]
        publisher_qs = Publisher.objects.annotate(
            latest_book_pubdate=Subquery(latest_book_pubdate_qs),
        ).annotate(count=Count('book'))
        with self.assertNumQueries(1) as ctx:
            list(publisher_qs)
        self.assertEqual(ctx[0]['sql'].count('SELECT'), 2)
        # The GROUP BY should not be by alias either.
        self.assertEqual(ctx[0]['sql'].lower().count('latest_book_pubdate'), 1)

    def test_aggregation_subquery_annotation_exists(self):
        latest_book_pubdate_qs = Book.objects.filter(
            publisher=OuterRef('pk')
        ).order_by('-pubdate').values('pubdate')[:1]
        publisher_qs = Publisher.objects.annotate(
            latest_book_pubdate=Subquery(latest_book_pubdate_qs),
            count=Count('book'),
        )
        self.assertTrue(publisher_qs.exists())

    def test_aggregation_exists_annotation(self):
        published_books = Book.objects.filter(publisher=OuterRef('pk'))
        publisher_qs = Publisher.objects.annotate(
            published_book=Exists(published_books),
            count=Count('book'),
        ).values_list('name', flat=True)
        self.assertCountEqual(list(publisher_qs), [
            'Apress',
            'Morgan Kaufmann',
            "Jonno's House of Books",
            'Prentice Hall',
            'Sams',
        ])

    def test_aggregation_subquery_annotation_values(self):
        """
        Subquery annotations and external aliases are excluded from the GROUP
        BY if they are not selected.
        """
        books_qs = Book.objects.annotate(
            first_author_the_same_age=Subquery(
                Author.objects.filter(
                    age=OuterRef('contact__friends__age'),
                ).order_by('age').values('id')[:1],
            )
        ).filter(
            publisher=self.p1,
            first_author_the_same_age__isnull=False,
        ).annotate(
            min_age=Min('contact__friends__age'),
        ).values('name', 'min_age').order_by('name')
        self.assertEqual(list(books_qs), [
            {'name': 'Practical Django Projects', 'min_age': 34},
            {
                'name': 'The Definitive Guide to Django: Web Development Done Right',
                'min_age': 29,
            },
        ])

    def test_aggregation_order_by_not_selected_annotation_values(self):
        result_asc = [
            self.b4.pk,
            self.b3.pk,
            self.b1.pk,
            self.b2.pk,
            self.b5.pk,
            self.b6.pk,
        ]
        result_desc = result_asc[::-1]
        tests = [
            ('min_related_age', result_asc),
            ('-min_related_age', result_desc),
            (F('min_related_age'), result_asc),
            (F('min_related_age').asc(), result_asc),
            (F('min_related_age').desc(), result_desc),
        ]
        for ordering, expected_result in tests:
            with self.subTest(ordering=ordering):
                books_qs = Book.objects.annotate(
                    min_age=Min('authors__age'),
                ).annotate(
                    min_related_age=Coalesce('min_age', 'contact__age'),
                ).order_by(ordering).values_list('pk', flat=True)
                self.assertEqual(list(books_qs), expected_result)

    @skipUnlessDBFeature('supports_subqueries_in_group_by')
    def test_group_by_subquery_annotation(self):
        """
        Subquery annotations are included in the GROUP BY if they are
        grouped against.
        """
        long_books_count_qs = Book.objects.filter(
            publisher=OuterRef('pk'),
            pages__gt=400,
        ).values(
            'publisher'
        ).annotate(count=Count('pk')).values('count')
        long_books_count_breakdown = Publisher.objects.values_list(
            Subquery(long_books_count_qs, IntegerField()),
        ).annotate(total=Count('*'))
        self.assertEqual(dict(long_books_count_breakdown), {None: 1, 1: 4})

    @skipUnlessDBFeature('supports_subqueries_in_group_by')
    def test_group_by_exists_annotation(self):
        """
        Exists annotations are included in the GROUP BY if they are
        grouped against.
        """
        long_books_qs = Book.objects.filter(
            publisher=OuterRef('pk'),
            pages__gt=800,
        )
        has_long_books_breakdown = Publisher.objects.values_list(
            Exists(long_books_qs),
        ).annotate(total=Count('*'))
        self.assertEqual(dict(has_long_books_breakdown), {True: 2, False: 3})

    def test_aggregation_subquery_annotation_related_field(self):
        publisher = Publisher.objects.create(name=self.a9.name, num_awards=2)
        book = Book.objects.create(
            isbn='159059999', name='Test book.', pages=819, rating=2.5,
            price=Decimal('14.44'), contact=self.a9, publisher=publisher,
            pubdate=datetime.date(2019, 12, 6),
        )
        book.authors.add(self.a5, self.a6, self.a7)
        books_qs = Book.objects.annotate(
            contact_publisher=Subquery(
                Publisher.objects.filter(
                    pk=OuterRef('publisher'),
                    name=OuterRef('contact__name'),
                ).values('name')[:1],
            )
        ).filter(
            contact_publisher__isnull=False,
        ).annotate(count=Count('authors'))
        self.assertSequenceEqual(books_qs, [book])