Ticket #23076: delete_fails_with_m2m_to_proxy_model.patch

tests/delete_regress/models.py

@@ -139 +139 @@
 
     class Meta:
         ordering = ['name']
+
+
+# Models for #23076
+
+
+class ConcretePhoto(Photo):
+    pass
+
+
+class M2MtoFile(models.Model):
+    # M2M to concrete proxy base
+    my_files = models.ManyToManyField(File)
+
+
+class M2MtoImage(M2MtoFile):
+    # M2M to proxy
+    my_images = models.ManyToManyField(Image)
+
+
+class M2MtoPhoto(M2MtoImage):
+    # M2M to proxy of proxy
+    my_photos = models.ManyToManyField(Photo)
+
+
+class M2MtoConcretePhoto(M2MtoPhoto):
+    # M2M to concrete proxy child
+    my_concrete_photos = models.ManyToManyField(ConcretePhoto)

tests/delete_regress/tests.py

@@ -10 +10 @@
 from .models import (Book, Award, AwardNote, Person, Child, Toy, PlayedWith,
     PlayedWithNote, Email, Researcher, Food, Eaten, Policy, Version, Location,
     Item, Image, File, Photo, FooFile, FooImage, FooPhoto, FooFileProxy, Login,
-    OrgUnit, OrderedPerson, House)
+    OrgUnit, OrderedPerson, House, M2MtoConcretePhoto, ConcretePhoto)
 
 
 # Can't run this test under SQLite, because you can't
@@ -269 +269 @@
             Image.objects.values_list().delete()
 
 
+# Error conditions don't show up under SQLite, needs FK constraints in DB
+@skipUnlessDBFeature('supports_foreign_keys')
+class ProxyDeleteM2MRelationshipsTest(TransactionTestCase):
+    """
+    Test that reverse FK component of M2M relationship to proxy models is
+    deleted when the relevant target model is deleted, to avoid errors like the
+    following in DBs that enforce FK integrity constraints:
+
+    - PostgreSQL:
+        IntegrityError: update or delete on table "TargetTable" violates
+        foreign key constraint "FKConstraint" on table "M2MThroughTable"
+        DETAIL:  Key (id)=(6) is still referenced from table "M2MThroughTable".
+    """
+
+    available_apps = ['delete_regress']
+
+    def setUp(self):
+        self.concrete_photo = ConcretePhoto.objects.create()
+        self.m2m_source = M2MtoConcretePhoto.objects.create()
+
+    def test_delete_with_m2m_to_concrete_base(self):
+        self.m2m_source.my_files.add(self.concrete_photo)
+
+        self.concrete_photo.delete()
+        self.assertEqual(len(self.m2m_source.my_files.all()), 0)
+
+    def test_delete_with_m2m_to_proxy(self):
+        self.m2m_source.my_images.add(self.concrete_photo)
+
+        self.concrete_photo.delete()
+        self.assertEqual(len(self.m2m_source.my_images.all()), 0)
+
+    def test_delete_with_m2m_to_proxy_of_proxy(self):
+        self.m2m_source.my_photos.add(self.concrete_photo)
+
+        self.concrete_photo.delete()
+        self.assertEqual(len(self.m2m_source.my_photos.all()), 0)
+
+    def test_delete_with_m2m_to_concrete_proxy_child(self):
+        self.m2m_source.my_concrete_photos.add(self.concrete_photo)
+
+        self.concrete_photo.delete()
+        self.assertEqual(len(self.m2m_source.my_concrete_photos.all()), 0)
+
+
 class Ticket19102Tests(TestCase):
     """
     Test different queries which alter the SELECT clause of the query. We