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>

2 files changed, 100 insertions, 0 deletions

diff --git a/tests/delete/models.py b/tests/delete/models.py
index 7f123b3396..bd9caf42a7 100644
--- a/tests/delete/models.py
+++ b/tests/delete/models.py
@@ -41,6 +41,46 @@ class RChildChild(RChild):
     pass
 
 
+class RelatedDbOptionGrandParent(models.Model):
+    pass
+
+
+class RelatedDbOptionParent(models.Model):
+    p = models.ForeignKey(RelatedDbOptionGrandParent, models.DB_CASCADE, null=True)
+
+
+class RelatedDbOption(models.Model):
+    name = models.CharField(max_length=30)
+    db_setnull = models.ForeignKey(
+        RelatedDbOptionParent,
+        models.DB_SET_NULL,
+        null=True,
+        related_name="db_setnull_set",
+    )
+    db_cascade = models.ForeignKey(
+        RelatedDbOptionParent, models.DB_CASCADE, related_name="db_cascade_set"
+    )
+
+
+class SetDefaultDbModel(models.Model):
+    db_setdefault = models.ForeignKey(
+        RelatedDbOptionParent,
+        models.DB_SET_DEFAULT,
+        db_default=models.Value(1),
+        related_name="db_setdefault_set",
+    )
+    db_setdefault_none = models.ForeignKey(
+        RelatedDbOptionParent,
+        models.DB_SET_DEFAULT,
+        db_default=None,
+        null=True,
+        related_name="db_setnull_nullable_set",
+    )
+
+    class Meta:
+        required_db_features = {"supports_on_delete_db_default"}
+
+
 class A(models.Model):
     name = models.CharField(max_length=30)
 
@@ -119,6 +159,15 @@ def create_a(name):
     return a
 
 
+def create_related_db_option(name):
+    a = RelatedDbOption(name=name)
+    for name in ["db_setnull", "db_cascade"]:
+        r = RelatedDbOptionParent.objects.create()
+        setattr(a, name, r)
+    a.save()
+    return a
+
+
 class M(models.Model):
     m2m = models.ManyToManyField(R, related_name="m_set")
     m2m_through = models.ManyToManyField(R, through="MR", related_name="m_through_set")
diff --git a/tests/delete/tests.py b/tests/delete/tests.py
index 59140b5c62..8d525d1e5f 100644
--- a/tests/delete/tests.py
+++ b/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 = []