Fixed #36806 -- Added system check for null kwarg in GeneratedField.

The null argument has no effect on GeneratedField since the nullability
of the column depends on the database and expression used.

1 files changed, 23 insertions, 0 deletions

diff --git a/tests/invalid_models_tests/test_ordinary_fields.py b/tests/invalid_models_tests/test_ordinary_fields.py
index 04c18d7ddd..e2ce74c673 100644
--- a/tests/invalid_models_tests/test_ordinary_fields.py
+++ b/tests/invalid_models_tests/test_ordinary_fields.py
@@ -1510,3 +1510,26 @@ class GeneratedFieldTests(TestCase):
             Model._meta.get_field("field").check(databases={"default"}),
             expected_warnings,
         )
+
+    @skipUnlessDBFeature("supports_stored_generated_columns")
+    def test_with_null_argument(self):
+        class Model(models.Model):
+            value = models.IntegerField()
+            field = models.GeneratedField(
+                expression=models.F("value") * 2,
+                output_field=models.IntegerField(),
+                db_persist=True,
+                null=True,
+            )
+
+        expected_warnings = [
+            DjangoWarning(
+                "null has no effect on GeneratedField.",
+                obj=Model._meta.get_field("field"),
+                id="fields.W225",
+            ),
+        ]
+        self.assertEqual(
+            Model._meta.get_field("field").check(databases={"default"}),
+            expected_warnings,
+        )