Ticket #16715: nested-foreign-key-test-r16914.patch

tests/regressiontests/nested_foreign_keys/tests.py

@@ +1 @@
+from django.test import TestCase
+
+from models import Movie, Event, Screening, ScreeningNullFK, Package, PackageNullFK
+
+
+# These are tests for #16715. The basic scheme is always the same: 3 models with
+# 2 relations. The first relation may be null, while the second is non-nullable.
+# In some cases, Django would pick the wrong join type for the second relation,
+# resulting in missing objects in the queryset.
+#
+#   Model A
+#   | (Relation A/B : nullable)
+#   Model B
+#   | (Relation B/C : non-nullable)
+#   Model C
+#
+# Because of the possibility of NULL rows resulting from the LEFT OUTER JOIN
+# between Model A and Model B (i.e. instances of A without reference to B),
+# the second join must also be LEFT OUTER JOIN, so that we do not ignore
+# instances of A that do not reference B.
+#
+# Relation A/B can either be an explicit foreign key or an implicit reverse
+# relation such as introduced by one-to-one relations (through multi-table
+# inheritance).
+class NestedForeignKeysTests(TestCase):
+    def setUp(self):
+        self.movie = Movie.objects.create(title='Monty Python and the Holy Grail')
+
+
+    # This test failed in #16715 because in some cases INNER JOIN was selected
+    # for the second foreign key relation instead of LEFT OUTER JOIN.
+    def testInheritance(self):
+        some_event = Event.objects.create()
+        screening = Screening.objects.create(movie=self.movie)
+
+        self.assertEqual(len(Event.objects.all()), 2)
+        self.assertEqual(len(Event.objects.select_related('screening')), 2)
+        # This failed.
+        self.assertEqual(len(Event.objects.select_related('screening__movie')), 2)
+
+        self.assertEqual(len(Event.objects.values()), 2)
+        self.assertEqual(len(Event.objects.values('screening__pk')), 2)
+        self.assertEqual(len(Event.objects.values('screening__movie__pk')), 2)
+        self.assertEqual(len(Event.objects.values('screening__movie__title')), 2)
+        # This failed.
+        self.assertEqual(len(Event.objects.values('screening__movie__pk', 'screening__movie__title')), 2)
+
+
+    # These all work because the second foreign key in the chain has null=True.
+    def testInheritanceNullFK(self):
+        some_event = Event.objects.create()
+        screening = ScreeningNullFK.objects.create(movie=None)
+        screening_with_movie = ScreeningNullFK.objects.create(movie=self.movie)
+
+        self.assertEqual(len(Event.objects.all()), 3)
+        self.assertEqual(len(Event.objects.select_related('screeningnullfk')), 3)
+        self.assertEqual(len(Event.objects.select_related('screeningnullfk__movie')), 3)
+
+        self.assertEqual(len(Event.objects.values()), 3)
+        self.assertEqual(len(Event.objects.values('screeningnullfk__pk')), 3)
+        self.assertEqual(len(Event.objects.values('screeningnullfk__movie__pk')), 3)
+        self.assertEqual(len(Event.objects.values('screeningnullfk__movie__title')), 3)
+        self.assertEqual(len(Event.objects.values('screeningnullfk__movie__pk', 'screeningnullfk__movie__title')), 3)
+
+
+    # This test failed in #16715 because in some cases INNER JOIN was selected
+    # for the second foreign key relation instead of LEFT OUTER JOIN.
+    def testExplicitForeignKey(self):
+        package = Package.objects.create()
+        screening = Screening.objects.create(movie=self.movie)
+        package_with_screening = Package.objects.create(screening=screening)
+
+        self.assertEqual(len(Package.objects.all()), 2)
+        self.assertEqual(len(Package.objects.select_related('screening')), 2)
+        self.assertEqual(len(Package.objects.select_related('screening__movie')), 2)
+
+        self.assertEqual(len(Package.objects.values()), 2)
+        self.assertEqual(len(Package.objects.values('screening__pk')), 2)
+        self.assertEqual(len(Package.objects.values('screening__movie__pk')), 2)
+        self.assertEqual(len(Package.objects.values('screening__movie__title')), 2)
+        # This failed.
+        self.assertEqual(len(Package.objects.values('screening__movie__pk', 'screening__movie__title')), 2)
+
+
+    # These all work because the second foreign key in the chain has null=True.
+    def testExplicitForeignKeyNullFK(self):
+        package = PackageNullFK.objects.create()
+        screening = ScreeningNullFK.objects.create(movie=None)
+        screening_with_movie = ScreeningNullFK.objects.create(movie=self.movie)
+        package_with_screening = PackageNullFK.objects.create(screening=screening)
+        package_with_screening_with_movie = PackageNullFK.objects.create(screening=screening_with_movie)
+
+        self.assertEqual(len(PackageNullFK.objects.all()), 3)
+        self.assertEqual(len(PackageNullFK.objects.select_related('screening')), 3)
+        self.assertEqual(len(PackageNullFK.objects.select_related('screening__movie')), 3)
+
+        self.assertEqual(len(PackageNullFK.objects.values()), 3)
+        self.assertEqual(len(PackageNullFK.objects.values('screening__pk')), 3)
+        self.assertEqual(len(PackageNullFK.objects.values('screening__movie__pk')), 3)
+        self.assertEqual(len(PackageNullFK.objects.values('screening__movie__title')), 3)
+        self.assertEqual(len(PackageNullFK.objects.values('screening__movie__pk', 'screening__movie__title')), 3)

tests/regressiontests/nested_foreign_keys/models.py

@@ +1 @@
+from django.db import models
+
+
+class Movie(models.Model):
+    title = models.CharField(max_length=200)
+
+
+class Event(models.Model):
+    pass
+
+
+class Screening(Event):
+    movie = models.ForeignKey(Movie)
+
+class ScreeningNullFK(Event):
+    movie = models.ForeignKey(Movie, null=True)
+
+
+class Package(models.Model):
+    screening = models.ForeignKey(Screening, null=True)
+
+class PackageNullFK(models.Model):
+    screening = models.ForeignKey(ScreeningNullFK, null=True)