[pull] main from django:main

django/db/models/fields/related_descriptors.py

@@ -180,6 +180,7 @@ def get_prefetch_querysets(self, instances, querysets=None):
                     "length of 1."
                 )
             queryset = querysets[0]
+            queryset._add_hints(instance=instances[0])
         else:
             _cloning_disabled = True
             queryset = self.get_queryset(instance=instances[0])._disable_cloning()
@@ -480,6 +481,7 @@ def get_prefetch_querysets(self, instances, querysets=None):
                     "length of 1."
                 )
             queryset = querysets[0]
+            queryset._add_hints(instance=instances[0])
         else:
             _cloning_disabled = True
             queryset = self.get_queryset(instance=instances[0])._disable_cloning()

django/db/models/fields/related_lookups.py

@@ -66,6 +66,7 @@ def get_prep_lookup(self):
                         -1
                     ]
                     self.rhs = [target_field.get_prep_value(v) for v in self.rhs]
+                    self.prepare_rhs = False
             elif not getattr(self.rhs, "has_select_fields", True) and not getattr(
                 self.lhs.field.target_field, "primary_key", False
             ):

docs/releases/6.1.1.txt

@@ -21,6 +21,11 @@ Bugfixes
   detect mixed ``on_delete`` variants for auto-created intermediate models for
   ``ManyToManyField``\s (:ticket:`37254`).
 
+* Fixed a regression in Django 6.1 where custom querysets used with
+  :class:`~django.db.models.Prefetch` for forward foreign key or reverse
+  one-to-one relationships were not routed using the parent queryset's
+  database (:ticket:`37300`).
+
 * Fixed a regression in Django 6.1 where HTML-safe strings, such as those
   created with :func:`~django.utils.safestring.mark_safe`, used as form media
   assets were treated as asset paths rather than being rendered verbatim

tests/prefetch_related/tests.py

@@ -1747,6 +1747,38 @@ def test_using_is_honored_custom_qs(self):
             )
         self.assertEqual(books, "Poems ()\n" "Sense and Sensibility ()\n")
 
+    def test_forward_fk_prefetch_custom_queryset_uses_parent_database(self):
+        book1 = Book.objects.using("default").create(title="Dive into Python")
+        Author.objects.using("default").create(name="Mark", first_book=book1)
+        book2 = Book.objects.using("other").create(title="Dive into Rust")
+        Author.objects.using("other").create(name="Mark", first_book=book2)
+
+        author = (
+            Author.objects.using("other")
+            .prefetch_related(Prefetch("first_book", queryset=Book.objects.all()))
+            .get(name="Mark")
+        )
+
+        self.assertEqual(author._state.db, "other")
+        self.assertEqual(author.first_book._state.db, "other")
+        self.assertEqual(author.first_book.title, "Dive into Rust")
+
+    def test_reverse_o2o_prefetch_custom_queryset_uses_parent_database(self):
+        BookWithYear.objects.using("default").create(title="Poems", published_year=2000)
+        BookWithYear.objects.using("other").create(title="Poems", published_year=2001)
+
+        book = (
+            Book.objects.using("other")
+            .prefetch_related(
+                Prefetch("bookwithyear", queryset=BookWithYear.objects.all())
+            )
+            .get(title="Poems")
+        )
+
+        self.assertEqual(book._state.db, "other")
+        self.assertEqual(book.bookwithyear._state.db, "other")
+        self.assertEqual(book.bookwithyear.published_year, 2001)
+
 
 class Ticket19607Tests(TestCase):
     @classmethod