from datetime import datetime from operator import attrgetter from django.db.models import F from django.db.models.functions import Upper from django.test import TestCase from .models import Article, Author, 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 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.assertSequenceEqual( Article.objects.order_by(F("author").desc(nulls_last=True)), [self.a4, self.a3, self.a1, self.a2], ) self.assertSequenceEqual( Article.objects.order_by(F("author").asc(nulls_last=True)), [self.a3, self.a4, self.a1, self.a2], ) self.assertSequenceEqual( Article.objects.order_by(Upper("author__name").desc(nulls_last=True)), [self.a4, self.a3, self.a1, self.a2], ) self.assertSequenceEqual( Article.objects.order_by(Upper("author__name").asc(nulls_last=True)), [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.assertSequenceEqual( Article.objects.order_by(F("author").asc(nulls_first=True)), [self.a1, self.a2, self.a3, self.a4], ) self.assertSequenceEqual( Article.objects.order_by(F("author").desc(nulls_first=True)), [self.a1, self.a2, self.a4, self.a3], ) self.assertSequenceEqual( Article.objects.order_by(Upper("author__name").asc(nulls_first=True)), [self.a1, self.a2, self.a3, self.a4], ) self.assertSequenceEqual( Article.objects.order_by(Upper("author__name").desc(nulls_first=True)), [self.a1, self.a2, self.a4, self.a3], ) 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( qs1, [ "Article 1", "Article 2", "Article 3", "Article 4", ], attrgetter("headline") ) self.assertQuerysetEqual( qs2, [ "Article 4", "Article 3", "Article 2", "Article 1", ], attrgetter("headline") ) 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_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_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') )