Fixed #34861 -- Fixed crash when adding GeneratedField with some expressions.

Co-authored-by: Simon Charette <charette.s@gmail.com>

django/db/models/fields/generated.py

@@ -61,12 +61,10 @@ class GeneratedField(Field):
             self.register_lookup(lookup, lookup_name=lookup_name)
 
     def generated_sql(self, connection):
-        return self._resolved_expression.as_sql(
+        compiler = connection.ops.compiler("SQLCompiler")(
-            compiler=connection.ops.compiler("SQLCompiler")(
+            self._query, connection=connection, using=None
-                self._query, connection=connection, using=None
-            ),
-            connection=connection,
         )
+        return compiler.compile(self._resolved_expression)
 
     def check(self, **kwargs):
         databases = kwargs.get("databases") or []

tests/schema/tests.py

@@ -32,6 +32,7 @@ from django.db.models import (
     FloatField,
     ForeignKey,
     ForeignObject,
+    GeneratedField,
     Index,
     IntegerField,
     JSONField,
@@ -50,7 +51,7 @@ from django.db.models import (
     UUIDField,
     Value,
 )
-from django.db.models.fields.json import KeyTextTransform
+from django.db.models.fields.json import KT, KeyTextTransform
 from django.db.models.functions import Abs, Cast, Collate, Lower, Random, Upper
 from django.db.models.indexes import IndexExpression
 from django.db.transaction import TransactionManagementError, atomic
@@ -810,6 +811,24 @@ class SchemaTests(TransactionTestCase):
         # Introspection treats BLOBs as TextFields
         self.assertEqual(columns["bits"][0], "TextField")
 
+    @isolate_apps("schema")
+    @skipUnlessDBFeature("supports_json_field", "supports_stored_generated_columns")
+    def test_add_generated_field_with_kt_model(self):
+        class GeneratedFieldKTModel(Model):
+            data = JSONField()
+            status = GeneratedField(expression=KT("data__status"), db_persist=True)
+
+            class Meta:
+                app_label = "schema"
+
+        with CaptureQueriesContext(connection) as ctx:
+            with connection.schema_editor() as editor:
+                editor.create_model(GeneratedFieldKTModel)
+        self.assertIs(
+            any("None" in query["sql"] for query in ctx.captured_queries),
+            False,
+        )
+
     @isolate_apps("schema")
     def test_add_auto_field(self):
         class AddAutoFieldModel(Model):