Fixed #32089 -- Fixed prefetch_related_objects() when some objects are already fetched.

Thanks Dennis Kliban for the report and Adam Johnson for the initial
patch.

Co-authored-by: Adam Johnson <me@adamj.eu>

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/prefetch_related/test_prefetch_related_objects.py b/tests/prefetch_related/test_prefetch_related_objects.py
index c0aa433b91..20d4da5a0a 100644
--- a/tests/prefetch_related/test_prefetch_related_objects.py
+++ b/tests/prefetch_related/test_prefetch_related_objects.py
@@ -97,6 +97,16 @@ class PrefetchRelatedObjectsTests(TestCase):
         with self.assertNumQueries(0):
             self.assertCountEqual(book1.authors.all(), [self.author1, self.author2, self.author3])
 
+    def test_prefetch_object_twice(self):
+        book1 = Book.objects.get(id=self.book1.id)
+        book2 = Book.objects.get(id=self.book2.id)
+        with self.assertNumQueries(1):
+            prefetch_related_objects([book1], Prefetch('authors'))
+        with self.assertNumQueries(1):
+            prefetch_related_objects([book1, book2], Prefetch('authors'))
+        with self.assertNumQueries(0):
+            self.assertCountEqual(book2.authors.all(), [self.author1])
+
     def test_prefetch_object_to_attr(self):
         book1 = Book.objects.get(id=self.book1.id)
         with self.assertNumQueries(1):
@@ -105,6 +115,22 @@ class PrefetchRelatedObjectsTests(TestCase):
         with self.assertNumQueries(0):
             self.assertCountEqual(book1.the_authors, [self.author1, self.author2, self.author3])
 
+    def test_prefetch_object_to_attr_twice(self):
+        book1 = Book.objects.get(id=self.book1.id)
+        book2 = Book.objects.get(id=self.book2.id)
+        with self.assertNumQueries(1):
+            prefetch_related_objects(
+                [book1],
+                Prefetch('authors', to_attr='the_authors'),
+            )
+        with self.assertNumQueries(1):
+            prefetch_related_objects(
+                [book1, book2],
+                Prefetch('authors', to_attr='the_authors'),
+            )
+        with self.assertNumQueries(0):
+            self.assertCountEqual(book2.the_authors, [self.author1])
+
     def test_prefetch_queryset(self):
         book1 = Book.objects.get(id=self.book1.id)
         with self.assertNumQueries(1):