From a3bb80dc3186bd4d11b7864268beb88595ab00fd Mon Sep 17 00:00:00 2001
From: Mariusz Felisiak <felisiak.mariusz@gmail.com>
Date: Mon, 14 Sep 2020 20:07:44 +0200
Subject: [PATCH] [3.1.x] Fixed #31990 -- Fixed QuerySet.ordered for GROUP BY
 queries on models with Meta.ordering.

Regression in 0ddb4ebf7bfcc4730c80a772dd146a49ef6895f6.

Thanks Julien Dutriaux for the report.
Backport of e11d05e0b488a3ff2b3c9d8f2e1e50f471750d6e from master
---
 django/db/models/query.py |  7 ++++++-
 docs/releases/3.1.2.txt   |  5 +++++
 tests/queries/tests.py    | 10 ++++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/django/db/models/query.py b/django/db/models/query.py
index e0eeccefa68..9c074772620 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -1220,7 +1220,12 @@ class QuerySet:
             return True
         if self.query.extra_order_by or self.query.order_by:
             return True
-        elif self.query.default_ordering and self.query.get_meta().ordering:
+        elif (
+            self.query.default_ordering and
+            self.query.get_meta().ordering and
+            # A default ordering doesn't affect GROUP BY queries.
+            not self.query.group_by
+        ):
             return True
         else:
             return False
diff --git a/docs/releases/3.1.2.txt b/docs/releases/3.1.2.txt
index 1243654bfb6..f9e45370ab9 100644
--- a/docs/releases/3.1.2.txt
+++ b/docs/releases/3.1.2.txt
@@ -11,3 +11,8 @@ Bugfixes
 
 * Fixed a bug in Django 3.1 where ``FileField`` instances with a callable
   storage were not correctly deconstructed (:ticket:`31941`).
+
+* Fixed a regression in Django 3.1 where the :attr:`.QuerySet.ordered`
+  attribute returned incorrectly ``True`` for ``GROUP BY`` queries (e.g.
+  ``.annotate().values()``) on models with ``Meta.ordering``. A model's
+  ``Meta.ordering`` doesn't affect such queries (:ticket:`31990`).
diff --git a/tests/queries/tests.py b/tests/queries/tests.py
index faa443adb14..11d5ec11ab1 100644
--- a/tests/queries/tests.py
+++ b/tests/queries/tests.py
@@ -2074,6 +2074,16 @@ class QuerysetOrderedTests(unittest.TestCase):
         self.assertIs(qs.ordered, False)
         self.assertIs(qs.order_by('num_notes').ordered, True)
 
+    def test_annotated_default_ordering(self):
+        qs = Tag.objects.annotate(num_notes=Count('pk'))
+        self.assertIs(qs.ordered, False)
+        self.assertIs(qs.order_by('name').ordered, True)
+
+    def test_annotated_values_default_ordering(self):
+        qs = Tag.objects.values('name').annotate(num_notes=Count('pk'))
+        self.assertIs(qs.ordered, False)
+        self.assertIs(qs.order_by('name').ordered, True)
+
 
 @skipUnlessDBFeature('allow_sliced_subqueries_with_in')
 class SubqueryTests(TestCase):