Fixed #34992 -- Fixed DatabaseFeatures.allows_group_by_selected_pks on MariaDB with ONLY_FULL_GROUP_BY sql mode.

Regression in 041551d.

Author: nathanielconroy

django/db/backends/mysql/features.py

@@ -6,7 +6,6 @@
 
 class DatabaseFeatures(BaseDatabaseFeatures):
     empty_fetchmany_value = ()
-    allows_group_by_selected_pks = True
     related_fields_match_type = True
     # MySQL doesn't support sliced subqueries with IN/ALL/ANY/SOME.
     allow_sliced_subqueries_with_in = False
@@ -319,3 +318,9 @@ def supports_expression_defaults(self):
     def has_native_uuid_field(self):
         is_mariadb = self.connection.mysql_is_mariadb
         return is_mariadb and self.connection.mysql_version >= (10, 7)
+
+    @cached_property
+    def allows_group_by_selected_pks(self):
+        if self.connection.mysql_is_mariadb:
+            return "ONLY_FULL_GROUP_BY" not in self.connection.sql_mode
+        return True

docs/releases/4.2.8.txt

@@ -27,3 +27,7 @@ Bugfixes
 
 * Fixed a regression in Django 4.2 where checkboxes in the admin would be
   centered on narrower screen widths (:ticket:`34994`).
+
+* Fixed a regression in Django 4.2 that caused a crash of querysets with
+  aggregations on MariaDB when the ``ONLY_FULL_GROUP_BY`` SQL mode was enabled
+  (:ticket:`34992`).

tests/backends/mysql/test_features.py

@@ -28,3 +28,21 @@ def test_allows_auto_pk_0(self):
             _connection.sql_mode = {"NO_AUTO_VALUE_ON_ZERO"}
             database_features = DatabaseFeatures(_connection)
             self.assertIs(database_features.allows_auto_pk_0, True)
+
+    def test_allows_group_by_selected_pks(self):
+        with mock.MagicMock() as _connection:
+            _connection.mysql_is_mariadb = False
+            database_features = DatabaseFeatures(_connection)
+            self.assertIs(database_features.allows_group_by_selected_pks, True)
+
+        with mock.MagicMock() as _connection:
+            _connection.mysql_is_mariadb = False
+            _connection.sql_mode = {}
+            database_features = DatabaseFeatures(_connection)
+            self.assertIs(database_features.allows_group_by_selected_pks, True)
+
+        with mock.MagicMock() as _connection:
+            _connection.mysql_is_mariadb = True
+            _connection.sql_mode = {"ONLY_FULL_GROUP_BY"}
+            database_features = DatabaseFeatures(_connection)
+            self.assertIs(database_features.allows_group_by_selected_pks, False)