from datetime import datetime from operator import attrgetter from django.core.exceptions import FieldError from django.db.models import ( CharField, DateTimeField, F, Max, OuterRef, Subquery, Value, ) from django.db.models.functions import Upper from django.test import TestCase from .models import Article, Author, ChildArticle, OrderedByFArticle, Reference class OrderingTests(TestCase): @classmethod def setUpTestData(cls): cls.a1 = Article.objects.create(headline="Article 1", pub_date=datetime(2005, 7, 26)) cls.a2 = Article.objects.create(headline="Article 2", pub_date=datetime(2005, 7, 27)) cls.a3 = Article.objects.create(headline="Article 3", pub_date=datetime(2005, 7, 27)) cls.a4 = Article.objects.create(headline="Article 4", pub_date=datetime(2005, 7, 28)) cls.author_1 = Author.objects.create(name="Name 1") cls.author_2 = Author.objects.create(name="Name 2") for i in range(2): Author.objects.create() def test_default_ordering(self): """ By default, Article.objects.all() orders by pub_date descending, then headline ascending. """ self.assertQuerysetEqual( Article.objects.all(), [ "Article 4", "Article 2", "Article 3", "Article 1", ], attrgetter("headline") ) # Getting a single item should work too: self.assertEqual(Article.objects.all()[0], self.a4) def test_default_ordering_override(self): """ Override ordering with order_by, which is in the same format as the ordering attribute in models. """ self.assertQuerysetEqual( Article.objects.order_by("headline"), [ "Article 1", "Article 2", "Article 3", "Article 4", ], attrgetter("headline") ) self.assertQuerysetEqual( Article.objects.order_by("pub_date", "-headline"), [ "Article 1", "Article 3", "Article 2", "Article 4", ], attrgetter("headline") ) def test_order_by_override(self): """ Only the last order_by has any effect (since they each override any previous ordering). """ self.assertQuerysetEqual( Article.objects.order_by("id"), [ "Article 1", "Article 2", "Article 3", "Article 4", ], attrgetter("headline") ) self.assertQuerysetEqual( Article.objects.order_by("id").order_by("-headline"), [ "Article 4", "Article 3", "Article 2", "Article 1", ], attrgetter("headline") ) def test_order_by_nulls_first_and_last(self): msg = "nulls_first and nulls_last are mutually exclusive" with self.assertRaisesMessage(ValueError, msg): Article.objects.order_by(F("author").desc(nulls_last=True, nulls_first=True)) def assertQuerysetEqualReversible(self, queryset, sequence): self.assertSequenceEqual(queryset, sequence) self.assertSequenceEqual(queryset.reverse(), list(reversed(sequence))) def test_order_by_nulls_last(self): Article.objects.filter(headline="Article 3").update(author=self.author_1) Article.objects.filter(headline="Article 4").update(author=self.author_2) # asc and desc are chainable with nulls_last. self.assertQuerysetEqualReversible( Article.objects.order_by(F("author").desc(nulls_last=True), 'headline'), [self.a4, self.a3, self.a1, self.a2], ) self.assertQuerysetEqualReversible( Article.objects.order_by(F("author").asc(nulls_last=True), 'headline'), [self.a3, self.a4, self.a1, self.a2], ) self.assertQuerysetEqualReversible( Article.objects.order_by(Upper("author__name").desc(nulls_last=True), 'headline'), [self.a4, self.a3, self.a1, self.a2], ) self.assertQuerysetEqualReversible( Article.objects.order_by(Upper("author__name").asc(nulls_last=True), 'headline'), [self.a3, self.a4, self.a1, self.a2], ) def test_order_by_nulls_first(self): Article.objects.filter(headline="Article 3").update(author=self.author_1) Article.objects.filter(headline="Article 4").update(author=self.author_2) # asc and desc are chainable with nulls_first. self.assertQuerysetEqualReversible( Article.objects.order_by(F("author").asc(nulls_first=True), 'headline'), [self.a1, self.a2, self.a3, self.a4], ) self.assertQuerysetEqualReversible( Article.objects.order_by(F("author").desc(nulls_first=True), 'headline'), [self.a1, self.a2, self.a4, self.a3], ) self.assertQuerysetEqualReversible( Article.objects.order_by(Upper("author__name").asc(nulls_first=True), 'headline'), [self.a1, self.a2, self.a3, self.a4], ) self.assertQuerysetEqualReversible( Article.objects.order_by(Upper("author__name").desc(nulls_first=True), 'headline'), [self.a1, self.a2, self.a4, self.a3], ) def test_orders_nulls_first_on_filtered_subquery(self): Article.objects.filter(headline='Article 1').update(author=self.author_1) Article.objects.filter(headline='Article 2').update(author=self.author_1) Article.objects.filter(headline='Article 4').update(author=self.author_2) Author.objects.filter(name__isnull=True).delete() author_3 = Author.objects.create(name='Name 3') article_subquery = Article.objects.filter( author=OuterRef('pk'), headline__icontains='Article', ).order_by().values('author').annotate( last_date=Max('pub_date'), ).values('last_date') self.assertQuerysetEqualReversible( Author.objects.annotate( last_date=Subquery(article_subquery, output_field=DateTimeField()) ).order_by( F('last_date').asc(nulls_first=True) ).distinct(), [author_3, self.author_1, self.author_2], ) def test_stop_slicing(self): """ Use the 'stop' part of slicing notation to limit the results. """ self.assertQuerysetEqual( Article.objects.order_by("headline")[:2], [ "Article 1", "Article 2", ], attrgetter("headline") ) def test_stop_start_slicing(self): """ Use the 'stop' and 'start' parts of slicing notation to offset the result list. """ self.assertQuerysetEqual( Article.objects.order_by("headline")[1:3], [ "Article 2", "Article 3", ], attrgetter("headline") ) def test_random_ordering(self): """ Use '?' to order randomly. """ self.assertEqual( len(list(Article.objects.order_by("?"))), 4 ) def test_reversed_ordering(self): """ Ordering can be reversed using the reverse() method on a queryset. This allows you to extract things like "the last two items" (reverse and then take the first two). """ self.assertQuerysetEqual( Article.objects.all().reverse()[:2], [ "Article 1", "Article 3", ], attrgetter("headline") ) def test_reverse_ordering_pure(self): qs1 = Article.objects.order_by(F('headline').asc()) qs2 = qs1.reverse() self.assertQuerysetEqual( qs2, [ 'Article 4', 'Article 3', 'Article 2', 'Article 1', ], attrgetter('headline'), ) self.assertQuerysetEqual( qs1, [ "Article 1", "Article 2", "Article 3", "Article 4", ], attrgetter("headline") ) def test_reverse_meta_ordering_pure(self): Article.objects.create( headline='Article 5', pub_date=datetime(2005, 7, 30), author=self.author_1, second_author=self.author_2, ) Article.objects.create( headline='Article 5', pub_date=datetime(2005, 7, 30), author=self.author_2, second_author=self.author_1, ) self.assertQuerysetEqual( Article.objects.filter(headline='Article 5').reverse(), ['Name 2', 'Name 1'], attrgetter('author.name'), ) self.assertQuerysetEqual( Article.objects.filter(headline='Article 5'), ['Name 1', 'Name 2'], attrgetter('author.name'), ) def test_no_reordering_after_slicing(self): msg = 'Cannot reverse a query once a slice has been taken.' qs = Article.objects.all()[0:2] with self.assertRaisesMessage(TypeError, msg): qs.reverse() with self.assertRaisesMessage(TypeError, msg): qs.last() def test_extra_ordering(self): """ Ordering can be based on fields included from an 'extra' clause """ self.assertQuerysetEqual( Article.objects.extra(select={"foo": "pub_date"}, order_by=["foo", "headline"]), [ "Article 1", "Article 2", "Article 3", "Article 4", ], attrgetter("headline") ) def test_extra_ordering_quoting(self): """ If the extra clause uses an SQL keyword for a name, it will be protected by quoting. """ self.assertQuerysetEqual( Article.objects.extra(select={"order": "pub_date"}, order_by=["order", "headline"]), [ "Article 1", "Article 2", "Article 3", "Article 4", ], attrgetter("headline") ) def test_extra_ordering_with_table_name(self): self.assertQuerysetEqual( Article.objects.extra(order_by=['ordering_article.headline']), [ "Article 1", "Article 2", "Article 3", "Article 4", ], attrgetter("headline") ) self.assertQuerysetEqual( Article.objects.extra(order_by=['-ordering_article.headline']), [ "Article 4", "Article 3", "Article 2", "Article 1", ], attrgetter("headline") ) def test_order_by_pk(self): """ 'pk' works as an ordering option in Meta. """ self.assertQuerysetEqual( Author.objects.all(), list(reversed(range(1, Author.objects.count() + 1))), attrgetter("pk"), ) def test_order_by_fk_attname(self): """ ordering by a foreign key by its attribute name prevents the query from inheriting its related model ordering option (#19195). """ for i in range(1, 5): author = Author.objects.get(pk=i) article = getattr(self, "a%d" % (5 - i)) article.author = author article.save(update_fields={'author'}) self.assertQuerysetEqual( Article.objects.order_by('author_id'), [ "Article 4", "Article 3", "Article 2", "Article 1", ], attrgetter("headline") ) def test_order_by_self_referential_fk(self): self.a1.author = Author.objects.create(editor=self.author_1) self.a1.save() self.a2.author = Author.objects.create(editor=self.author_2) self.a2.save() self.assertQuerysetEqual( Article.objects.filter(author__isnull=False).order_by('author__editor'), ['Article 2', 'Article 1'], attrgetter('headline'), ) def test_order_by_f_expression(self): self.assertQuerysetEqual( Article.objects.order_by(F('headline')), [ "Article 1", "Article 2", "Article 3", "Article 4", ], attrgetter("headline") ) self.assertQuerysetEqual( Article.objects.order_by(F('headline').asc()), [ "Article 1", "Article 2", "Article 3", "Article 4", ], attrgetter("headline") ) self.assertQuerysetEqual( Article.objects.order_by(F('headline').desc()), [ "Article 4", "Article 3", "Article 2", "Article 1", ], attrgetter("headline") ) def test_order_by_f_expression_duplicates(self): """ A column may only be included once (the first occurrence) so we check to ensure there are no duplicates by inspecting the SQL. """ qs = Article.objects.order_by(F('headline').asc(), F('headline').desc()) sql = str(qs.query).upper() fragment = sql[sql.find('ORDER BY'):] self.assertEqual(fragment.count('HEADLINE'), 1) self.assertQuerysetEqual( qs, [ "Article 1", "Article 2", "Article 3", "Article 4", ], attrgetter("headline") ) qs = Article.objects.order_by(F('headline').desc(), F('headline').asc()) sql = str(qs.query).upper() fragment = sql[sql.find('ORDER BY'):] self.assertEqual(fragment.count('HEADLINE'), 1) self.assertQuerysetEqual( qs, [ "Article 4", "Article 3", "Article 2", "Article 1", ], attrgetter("headline") ) def test_order_by_constant_value(self): # Order by annotated constant from selected columns. qs = Article.objects.annotate( constant=Value('1', output_field=CharField()), ).order_by('constant', '-headline') self.assertSequenceEqual(qs, [self.a4, self.a3, self.a2, self.a1]) # Order by annotated constant which is out of selected columns. self.assertSequenceEqual( qs.values_list('headline', flat=True), [ 'Article 4', 'Article 3', 'Article 2', 'Article 1', ], ) # Order by constant. qs = Article.objects.order_by(Value('1', output_field=CharField()), '-headline') self.assertSequenceEqual(qs, [self.a4, self.a3, self.a2, self.a1]) def test_order_by_constant_value_without_output_field(self): msg = 'Cannot resolve expression type, unknown output_field' qs = Article.objects.annotate(constant=Value('1')).order_by('constant') for ordered_qs in ( qs, qs.values('headline'), Article.objects.order_by(Value('1')), ): with self.subTest(ordered_qs=ordered_qs), self.assertRaisesMessage(FieldError, msg): ordered_qs.first() def test_related_ordering_duplicate_table_reference(self): """ An ordering referencing a model with an ordering referencing a model multiple time no circular reference should be detected (#24654). """ first_author = Author.objects.create() second_author = Author.objects.create() self.a1.author = first_author self.a1.second_author = second_author self.a1.save() self.a2.author = second_author self.a2.second_author = first_author self.a2.save() r1 = Reference.objects.create(article_id=self.a1.pk) r2 = Reference.objects.create(article_id=self.a2.pk) self.assertSequenceEqual(Reference.objects.all(), [r2, r1]) def test_default_ordering_by_f_expression(self): """F expressions can be used in Meta.ordering.""" articles = OrderedByFArticle.objects.all() articles.filter(headline='Article 2').update(author=self.author_2) articles.filter(headline='Article 3').update(author=self.author_1) self.assertQuerysetEqual( articles, ['Article 1', 'Article 4', 'Article 3', 'Article 2'], attrgetter('headline') ) def test_order_by_ptr_field_with_default_ordering_by_expression(self): ca1 = ChildArticle.objects.create( headline='h2', pub_date=datetime(2005, 7, 27), author=self.author_2, ) ca2 = ChildArticle.objects.create( headline='h2', pub_date=datetime(2005, 7, 27), author=self.author_1, ) ca3 = ChildArticle.objects.create( headline='h3', pub_date=datetime(2005, 7, 27), author=self.author_1, ) ca4 = ChildArticle.objects.create(headline='h1', pub_date=datetime(2005, 7, 28)) articles = ChildArticle.objects.order_by('article_ptr') self.assertSequenceEqual(articles, [ca4, ca2, ca1, ca3])