from django.test import TestCase from .models import Article, Car, Driver, Reporter class ManyToOneNullTests(TestCase): @classmethod def setUpTestData(cls): # Create a Reporter. cls.r = Reporter(name="John Smith") cls.r.save() # Create an Article. cls.a = Article(headline="First", reporter=cls.r) cls.a.save() # Create an Article via the Reporter object. cls.a2 = cls.r.article_set.create(headline="Second") # Create an Article with no Reporter by passing "reporter=None". cls.a3 = Article(headline="Third", reporter=None) cls.a3.save() # Create another article and reporter cls.r2 = Reporter(name="Paul Jones") cls.r2.save() cls.a4 = cls.r2.article_set.create(headline="Fourth") def test_get_related(self): self.assertEqual(self.a.reporter.id, self.r.id) # Article objects have access to their related Reporter objects. r = self.a.reporter self.assertEqual(r.id, self.r.id) def test_created_via_related_set(self): self.assertEqual(self.a2.reporter.id, self.r.id) def test_related_set(self): # Reporter objects have access to their related Article objects. self.assertSequenceEqual(self.r.article_set.all(), [self.a, self.a2]) self.assertSequenceEqual( self.r.article_set.filter(headline__startswith="Fir"), [self.a] ) self.assertEqual(self.r.article_set.count(), 2) def test_created_without_related(self): self.assertIsNone(self.a3.reporter) # Need to reget a3 to refresh the cache a3 = Article.objects.get(pk=self.a3.pk) with self.assertRaises(AttributeError): getattr(a3.reporter, "id") # Accessing an article's 'reporter' attribute returns None # if the reporter is set to None. self.assertIsNone(a3.reporter) # To retrieve the articles with no reporters set, use "reporter__isnull=True". self.assertSequenceEqual( Article.objects.filter(reporter__isnull=True), [self.a3] ) # We can achieve the same thing by filtering for the case where the # reporter is None. self.assertSequenceEqual(Article.objects.filter(reporter=None), [self.a3]) # Set the reporter for the Third article self.assertSequenceEqual(self.r.article_set.all(), [self.a, self.a2]) self.r.article_set.add(a3) self.assertSequenceEqual( self.r.article_set.all(), [self.a, self.a2, self.a3], ) # Remove an article from the set, and check that it was removed. self.r.article_set.remove(a3) self.assertSequenceEqual(self.r.article_set.all(), [self.a, self.a2]) self.assertSequenceEqual( Article.objects.filter(reporter__isnull=True), [self.a3] ) def test_remove_from_wrong_set(self): self.assertSequenceEqual(self.r2.article_set.all(), [self.a4]) # Try to remove a4 from a set it does not belong to with self.assertRaises(Reporter.DoesNotExist): self.r.article_set.remove(self.a4) self.assertSequenceEqual(self.r2.article_set.all(), [self.a4]) def test_set(self): # Use manager.set() to allocate ForeignKey. Null is legal, so existing # members of the set that are not in the assignment set are set to null. self.r2.article_set.set([self.a2, self.a3]) self.assertSequenceEqual(self.r2.article_set.all(), [self.a2, self.a3]) # Use manager.set(clear=True) self.r2.article_set.set([self.a3, self.a4], clear=True) self.assertSequenceEqual(self.r2.article_set.all(), [self.a4, self.a3]) # Clear the rest of the set self.r2.article_set.set([]) self.assertSequenceEqual(self.r2.article_set.all(), []) self.assertSequenceEqual( Article.objects.filter(reporter__isnull=True), [self.a4, self.a2, self.a3], ) def test_set_clear_non_bulk(self): # 2 queries for clear(), 1 for add(), and 1 to select objects. with self.assertNumQueries(4): self.r.article_set.set([self.a], bulk=False, clear=True) def test_assign_clear_related_set(self): # Use descriptor assignment to allocate ForeignKey. Null is legal, so # existing members of the set that are not in the assignment set are # set to null. self.r2.article_set.set([self.a2, self.a3]) self.assertSequenceEqual(self.r2.article_set.all(), [self.a2, self.a3]) # Clear the rest of the set self.r.article_set.clear() self.assertSequenceEqual(self.r.article_set.all(), []) self.assertSequenceEqual( Article.objects.filter(reporter__isnull=True), [self.a, self.a4], ) def test_assign_with_queryset(self): # Querysets used in reverse FK assignments are pre-evaluated # so their value isn't affected by the clearing operation in # RelatedManager.set() (#19816). self.r2.article_set.set([self.a2, self.a3]) qs = self.r2.article_set.filter(headline="Second") self.r2.article_set.set(qs) self.assertEqual(1, self.r2.article_set.count()) self.assertEqual(1, qs.count()) def test_add_efficiency(self): r = Reporter.objects.create() articles = [] for _ in range(3): articles.append(Article.objects.create()) with self.assertNumQueries(1): r.article_set.add(*articles) self.assertEqual(r.article_set.count(), 3) def test_clear_efficiency(self): r = Reporter.objects.create() for _ in range(3): r.article_set.create() with self.assertNumQueries(1): r.article_set.clear() self.assertEqual(r.article_set.count(), 0) def test_related_null_to_field(self): c1 = Car.objects.create() d1 = Driver.objects.create() self.assertIs(d1.car, None) with self.assertNumQueries(0): self.assertEqual(list(c1.drivers.all()), []) def test_unsaved(self): msg = ( "'Car' instance needs to have a primary key value before this relationship " "can be used." ) with self.assertRaisesMessage(ValueError, msg): Car(make="Ford").drivers.all() def test_related_null_to_field_related_managers(self): car = Car.objects.create(make=None) driver = Driver.objects.create() msg = ( f'"{car!r}" needs to have a value for field "make" before this ' f"relationship can be used." ) with self.assertRaisesMessage(ValueError, msg): car.drivers.add(driver) with self.assertRaisesMessage(ValueError, msg): car.drivers.create() with self.assertRaisesMessage(ValueError, msg): car.drivers.get_or_create() with self.assertRaisesMessage(ValueError, msg): car.drivers.update_or_create() with self.assertRaisesMessage(ValueError, msg): car.drivers.remove(driver) with self.assertRaisesMessage(ValueError, msg): car.drivers.clear() with self.assertRaisesMessage(ValueError, msg): car.drivers.set([driver]) with self.assertNumQueries(0): self.assertEqual(car.drivers.count(), 0)