Fixed #31095 -- Made RelatedManager.set() preserve existing m2m relations with an invalid type.

1 files changed, 13 insertions, 0 deletions

diff --git a/tests/many_to_many/tests.py b/tests/many_to_many/tests.py
index 79d0fa420c..b4314580ec 100644
--- a/tests/many_to_many/tests.py
+++ b/tests/many_to_many/tests.py
@@ -469,6 +469,19 @@ class ManyToManyTests(TestCase):
         self.a4.publications.set([], clear=True)
         self.assertQuerysetEqual(self.a4.publications.all(), [])
 
+    def test_set_existing_different_type(self):
+        # Existing many-to-many relations remain the same for values provided
+        # with a different type.
+        ids = set(Publication.article_set.through.objects.filter(
+            article__in=[self.a4, self.a3],
+            publication=self.p2,
+        ).values_list('id', flat=True))
+        self.p2.article_set.set([str(self.a4.pk), str(self.a3.pk)])
+        new_ids = set(Publication.article_set.through.objects.filter(
+            publication=self.p2,
+        ).values_list('id', flat=True))
+        self.assertEqual(ids, new_ids)
+
     def test_assign_forward(self):
         msg = (
             "Direct assignment to the reverse side of a many-to-many set is "