Fixed #21961 -- Added support for database-level delete options for ForeignKey.

Thanks Simon Charette for pair programming.

Co-authored-by: Nick Stefan <NickStefan12@gmail.com>
Co-authored-by: Akash Kumar Sen <71623442+Akash-Kumar-Sen@users.noreply.github.com>
Co-authored-by: Simon Charette <charette.s@gmail.com>

tests/delete/tests.py

@@ -34,11 +34,16 @@ from .models import (
     RChild,
     RChildChild,
     Referrer,
+    RelatedDbOption,
+    RelatedDbOptionGrandParent,
+    RelatedDbOptionParent,
     RProxy,
     S,
+    SetDefaultDbModel,
     T,
     User,
     create_a,
+    create_related_db_option,
     get_default_r,
 )
 
@@ -76,18 +81,48 @@ class OnDeleteTests(TestCase):
         a = A.objects.get(pk=a.pk)
         self.assertIsNone(a.setnull)
 
+    def test_db_setnull(self):
+        a = create_related_db_option("db_setnull")
+        a.db_setnull.delete()
+        a = RelatedDbOption.objects.get(pk=a.pk)
+        self.assertIsNone(a.db_setnull)
+
     def test_setdefault(self):
         a = create_a("setdefault")
         a.setdefault.delete()
         a = A.objects.get(pk=a.pk)
         self.assertEqual(self.DEFAULT, a.setdefault.pk)
 
+    @skipUnlessDBFeature("supports_on_delete_db_default")
+    def test_db_setdefault(self):
+        # Object cannot be created on the module initialization, use hardcoded
+        # PKs instead.
+        r = RelatedDbOptionParent.objects.create(pk=2)
+        default_r = RelatedDbOptionParent.objects.create(pk=1)
+        set_default_db_obj = SetDefaultDbModel.objects.create(db_setdefault=r)
+        set_default_db_obj.db_setdefault.delete()
+        set_default_db_obj = SetDefaultDbModel.objects.get(pk=set_default_db_obj.pk)
+        self.assertEqual(set_default_db_obj.db_setdefault, default_r)
+
     def test_setdefault_none(self):
         a = create_a("setdefault_none")
         a.setdefault_none.delete()
         a = A.objects.get(pk=a.pk)
         self.assertIsNone(a.setdefault_none)
 
+    @skipUnlessDBFeature("supports_on_delete_db_default")
+    def test_db_setdefault_none(self):
+        # Object cannot be created on the module initialization, use hardcoded
+        # PKs instead.
+        r = RelatedDbOptionParent.objects.create(pk=2)
+        default_r = RelatedDbOptionParent.objects.create(pk=1)
+        set_default_db_obj = SetDefaultDbModel.objects.create(
+            db_setdefault_none=r, db_setdefault=default_r
+        )
+        set_default_db_obj.db_setdefault_none.delete()
+        set_default_db_obj = SetDefaultDbModel.objects.get(pk=set_default_db_obj.pk)
+        self.assertIsNone(set_default_db_obj.db_setdefault_none)
+
     def test_cascade(self):
         a = create_a("cascade")
         a.cascade.delete()
@@ -359,6 +394,22 @@ class DeletionTests(TestCase):
         self.assertNumQueries(5, s.delete)
         self.assertFalse(S.objects.exists())
 
+    def test_db_cascade(self):
+        related_db_op = RelatedDbOptionParent.objects.create(
+            p=RelatedDbOptionGrandParent.objects.create()
+        )
+        RelatedDbOption.objects.bulk_create(
+            [
+                RelatedDbOption(db_cascade=related_db_op)
+                for _ in range(2 * GET_ITERATOR_CHUNK_SIZE)
+            ]
+        )
+        with self.assertNumQueries(1):
+            results = related_db_op.delete()
+            self.assertEqual(results, (1, {"delete.RelatedDbOptionParent": 1}))
+        self.assertFalse(RelatedDbOption.objects.exists())
+        self.assertFalse(RelatedDbOptionParent.objects.exists())
+
     def test_instance_update(self):
         deleted = []
         related_setnull_sets = []