Fixed #34819 -- Made GenericForeignKey prefetching use matching pk representations.

Ensured that rel_obj_attr and instance_attr return matching (pk, cls) tuples
in GenericForeignKey.get_prefetch_queryset(), preventing mismatches when
prefetching related objects where pk and get_prep_value() differ. Using
value_to_string() also makes this code compatible with composite primary keys.

1 files changed, 9 insertions, 0 deletions

diff --git a/tests/prefetch_related/models.py b/tests/prefetch_related/models.py
index 2f37cde1c8..e12eabdfb2 100644
--- a/tests/prefetch_related/models.py
+++ b/tests/prefetch_related/models.py
@@ -216,6 +216,15 @@ class Comment(models.Model):
         ordering = ["id"]
 
 
+class ArticleCustomUUID(models.Model):
+    class CustomUUIDField(models.UUIDField):
+        def get_prep_value(self, value):
+            return str(value)
+
+    id = CustomUUIDField(primary_key=True, default=uuid.uuid4)
+    name = models.CharField(max_length=30)
+
+
 # Models for lookup ordering tests