[5.0.x] Fixed #35336 -- Addressed crash when adding a GeneratedField with % literals.

A longer term solution is likely to have a better separation of parametrized
DDL altogether to handle checks, constraints, defaults, and generated fields
but such a change would require a significant refactor that isn't suitable
for a backport.

Thanks Adrian Garcia for the report.

Backport of 888b9042b3 from main

django/db/backends/base/schema.py

@@ -317,9 +317,9 @@ class BaseDatabaseSchemaEditor:
             if default_value is not None:
                 column_default = "DEFAULT " + self._column_default_sql(field)
                 if self.connection.features.requires_literal_defaults:
-                    # Some databases can't take defaults as a parameter (Oracle).
-                    # If this is the case, the individual schema backend should
-                    # implement prepare_default().
+                    # Some databases can't take defaults as a parameter
+                    # (Oracle, SQLite). If this is the case, the individual
+                    # schema backend should implement prepare_default().
                     yield column_default % self.prepare_default(default_value)
                 else:
                     yield column_default
@@ -333,7 +333,9 @@ class BaseDatabaseSchemaEditor:
         ):
             null = True
         if field.generated:
-            yield self._column_generated_sql(field)
+            generated_sql, generated_params = self._column_generated_sql(field)
+            params.extend(generated_params)
+            yield generated_sql
         elif not null:
             yield "NOT NULL"
         elif not self.connection.features.implied_column_null:
@@ -420,7 +422,7 @@ class BaseDatabaseSchemaEditor:
         compiler = query.get_compiler(connection=self.connection)
         default_sql, params = compiler.compile(db_default)
         if self.connection.features.requires_literal_defaults:
-            # Some databases doesn't support parameterized defaults (Oracle,
+            # Some databases don't support parameterized defaults (Oracle,
             # SQLite). If this is the case, the individual schema backend
             # should implement prepare_default().
             default_sql %= tuple(self.prepare_default(p) for p in params)
@@ -431,9 +433,10 @@ class BaseDatabaseSchemaEditor:
         """Return the SQL to use in a GENERATED ALWAYS clause."""
         expression_sql, params = field.generated_sql(self.connection)
         persistency_sql = "STORED" if field.db_persist else "VIRTUAL"
-        if params:
+        if self.connection.features.requires_literal_defaults:
             expression_sql = expression_sql % tuple(self.quote_value(p) for p in params)
-        return f"GENERATED ALWAYS AS ({expression_sql}) {persistency_sql}"
+            params = ()
+        return f"GENERATED ALWAYS AS ({expression_sql}) {persistency_sql}", params
 
     @staticmethod
     def _effective_default(field):
@@ -484,7 +487,7 @@ class BaseDatabaseSchemaEditor:
         """
         sql, params = self.table_sql(model)
         # Prevent using [] as params, in the case a literal '%' is used in the
-        # definition.
+        # definition on backends that don't support parametrized DDL.
         self.execute(sql, params or None)
 
         if self.connection.features.supports_comments:
@@ -747,7 +750,9 @@ class BaseDatabaseSchemaEditor:
             "column": self.quote_name(field.column),
             "definition": definition,
         }
-        self.execute(sql, params)
+        # Prevent using [] as params, in the case a literal '%' is used in the
+        # definition on backends that don't support parametrized DDL.
+        self.execute(sql, params or None)
         # Drop the default if we need to
         if (
             field.db_default is NOT_PROVIDED

django/db/backends/oracle/schema.py

@@ -198,9 +198,7 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
         return self.normalize_name(for_name + "_" + suffix)
 
     def prepare_default(self, value):
-        # Replace % with %% as %-formatting is applied in
-        # FormatStylePlaceholderCursor._fix_for_params().
-        return self.quote_value(value).replace("%", "%%")
+        return self.quote_value(value)
 
     def _field_should_be_indexed(self, model, field):
         create_index = super()._field_should_be_indexed(model, field)

docs/releases/5.0.4.txt

@@ -24,3 +24,7 @@ Bugfixes
 
 * Fixed a crash in Django 5.0 when performing queries involving table aliases
   and lookups on a ``GeneratedField`` of the aliased table (:ticket:`35344`).
+
+* Fixed a bug in Django 5.0 that caused a migration crash when adding a
+  ``GeneratedField`` relying on the ``__contains`` or ``__icontains``
+  lookups or using a ``Value`` containing a ``"%"`` (:ticket:`35336`).

tests/schema/tests.py

@@ -54,7 +54,16 @@ from django.db.models import (
     Value,
 )
 from django.db.models.fields.json import KT, KeyTextTransform
-from django.db.models.functions import Abs, Cast, Collate, Lower, Random, Round, Upper
+from django.db.models.functions import (
+    Abs,
+    Cast,
+    Collate,
+    Concat,
+    Lower,
+    Random,
+    Round,
+    Upper,
+)
 from django.db.models.indexes import IndexExpression
 from django.db.transaction import TransactionManagementError, atomic
 from django.test import (
@@ -892,6 +901,39 @@ class SchemaTests(TransactionTestCase):
         with connection.schema_editor() as editor:
             editor.create_model(GeneratedFieldOutputFieldModel)
 
+    @isolate_apps("schema")
+    @skipUnlessDBFeature("supports_stored_generated_columns")
+    def test_add_generated_field_contains(self):
+        class GeneratedFieldContainsModel(Model):
+            text = TextField(default="foo")
+            generated = GeneratedField(
+                expression=Concat("text", Value("%")),
+                db_persist=True,
+                output_field=TextField(),
+            )
+
+            class Meta:
+                app_label = "schema"
+
+        with connection.schema_editor() as editor:
+            editor.create_model(GeneratedFieldContainsModel)
+
+        field = GeneratedField(
+            expression=Q(text__icontains="FOO"),
+            db_persist=True,
+            output_field=BooleanField(),
+        )
+        field.contribute_to_class(GeneratedFieldContainsModel, "contains_foo")
+
+        with connection.schema_editor() as editor:
+            editor.add_field(GeneratedFieldContainsModel, field)
+
+        obj = GeneratedFieldContainsModel.objects.create()
+        obj.refresh_from_db()
+        self.assertEqual(obj.text, "foo")
+        self.assertEqual(obj.generated, "foo%")
+        self.assertIs(obj.contains_foo, True)
+
     @isolate_apps("schema")
     def test_add_auto_field(self):
         class AddAutoFieldModel(Model):