[pull] main from django:main

django/db/models/fields/generated.py

@@ -30,7 +30,6 @@ def __init__(self, *, expression, output_field, db_persist, **kwargs):
         self.expression = expression
         self.output_field = output_field
         self.db_persist = db_persist
-        self.has_null_arg = "null" in kwargs
         super().__init__(**kwargs)
 
     @cached_property
@@ -83,7 +82,6 @@ def check(self, **kwargs):
             *super().check(**kwargs),
             *self._check_supported(databases),
             *self._check_persistence(databases),
-            *self._check_ignored_options(databases),
         ]
         output_field_clone = self.output_field.clone()
         output_field_clone.model = self.model
@@ -190,20 +188,6 @@ def _check_persistence(self, databases):
                 )
         return errors
 
-    def _check_ignored_options(self, databases):
-        warnings = []
-
-        if self.has_null_arg:
-            warnings.append(
-                checks.Warning(
-                    "null has no effect on GeneratedField.",
-                    obj=self,
-                    id="fields.W225",
-                )
-            )
-
-        return warnings
-
     def deconstruct(self):
         name, path, args, kwargs = super().deconstruct()
         del kwargs["blank"]

docs/ref/checks.txt

@@ -234,7 +234,8 @@ Model fields
   ``GeneratedField``\s.
 * **fields.E223**: ``GeneratedField.output_field`` has errors: ...
 * **fields.W224**: ``GeneratedField.output_field`` has warnings: ...
-* **fields.W225**: ``null`` has no effect on ``GeneratedField``.
+* **fields.W225**: ``null`` has no effect on ``GeneratedField``. *This check
+  is removed in Django 6.1.2.*
 * **fields.E900**: ``IPAddressField`` has been removed except for support in
   historical migrations.
 * **fields.W900**: ``IPAddressField`` has been deprecated. Support for it

docs/ref/models/fields.txt

@@ -1366,9 +1366,6 @@ materialized view.
 .. _PostgreSQL: https://www.postgresql.org/docs/current/ddl-generated-columns.html
 .. _SQLite: https://www.sqlite.org/gencol.html#limitations
 
-:attr:`~Field.null` has no effect on ``GeneratedField`` since whether the
-column is nullable depends on the database and expression used.
-
 ``GenericIPAddressField``
 -------------------------
 

docs/releases/6.1.2.txt

@@ -11,3 +11,6 @@ Bugfixes
 
 * Fixed a data loss issue in Django 4.0 where :ref:`network rasters
   <gdal-raster-network>` were deleted by GeoDjango when closed.
+
+* Fixed a bug in Django 6.1 where the ``fields.W225`` system check incorrectly
+  warned that ``null`` has no effect on ``GeneratedField`` (:ticket:`37348`).

tests/invalid_models_tests/test_ordinary_fields.py

@@ -1510,26 +1510,3 @@ class Model(models.Model):
             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,
-        )

tests/model_fields/models.py

@@ -655,6 +655,7 @@ class GeneratedModelNull(models.Model):
         expression=Lower("name"),
         output_field=models.CharField(max_length=10),
         db_persist=True,
+        null=True,
     )
 
     class Meta:
@@ -667,6 +668,7 @@ class GeneratedModelNullVirtual(models.Model):
         expression=Lower("name"),
         output_field=models.CharField(max_length=10),
         db_persist=False,
+        null=True,
     )
 
     class Meta:

tests/model_fields/test_generatedfield.py

@@ -381,6 +381,15 @@ def test_nullable(self):
         with self.assertNumQueries(expected_num_queries):
             self.assertEqual(m2.lower_name, "name")
 
+    def test_nullable_exclude(self):
+        m1 = self.nullable_model.objects.create()
+        m2 = self.nullable_model.objects.create(name="NaMe")
+        self.nullable_model.objects.create(name="Other")
+        self.assertSequenceEqual(
+            self.nullable_model.objects.exclude(lower_name="other").order_by("pk"),
+            [m1, m2],
+        )
+
 
 @skipUnlessDBFeature("supports_stored_generated_columns")
 class StoredGeneratedFieldTests(GeneratedFieldTestMixin, TestCase):