[5.2.x] Fixed #36432 -- Fixed a prefetch_related crash on related target subclass queryset.

Regression in 626d77e52a3f247358514bcf51c761283968099c.

Refs #36116.

Thanks Cornelis Poppema for the excellent report.

Backport of 08187c94ed02c45ad40a32244dedeaa7ac71ca87 from main.

django/db/models/fields/related_descriptors.py

@@ -183,8 +183,11 @@ class ForwardManyToOneDescriptor:
         rel_obj_attr = self.field.get_foreign_related_value
         instance_attr = self.field.get_local_related_value
         instances_dict = {instance_attr(inst): inst for inst in instances}
-        related_fields = self.field.foreign_related_fields
         remote_field = self.field.remote_field
+        related_fields = [
+            queryset.query.resolve_ref(field.name).target
+            for field in self.field.foreign_related_fields
+        ]
         queryset = queryset.filter(
             TupleIn(
                 ColPairs(

docs/releases/5.2.2.txt

@@ -43,3 +43,7 @@ Bugfixes
   <django.http.HttpRequest.get_preferred_type>` did not account for media type
   parameters in ``Accept`` headers, reducing specificity in content negotiation
   (:ticket:`36411`).
+
+* Fixed a regression in Django 5.2 that caused a crash when using
+  ``QuerySet.prefetch_related()`` to prefetch a foreign key with a ``Prefetch``
+  queryset for a subclass of the foreign target (:ticket:`36432`).

tests/prefetch_related/models.py

@@ -271,6 +271,10 @@ class Employee(models.Model):
         ordering = ["id"]
 
 
+class SelfDirectedEmployee(Employee):
+    pass
+
+
 # Ticket #19607
 
 

tests/prefetch_related/tests.py

@@ -39,6 +39,7 @@ from .models import (
     Qualification,
     Reader,
     Room,
+    SelfDirectedEmployee,
     TaggedItem,
     Teacher,
     WordEntry,
@@ -435,6 +436,18 @@ class PrefetchRelatedTests(TestDataMixin, TestCase):
             authors[1].active_favorite_authors, [self.author3, self.author4]
         )
 
+    def test_prefetch_queryset_child_class(self):
+        employee = SelfDirectedEmployee.objects.create(name="Foo")
+        employee.boss = employee
+        employee.save()
+        with self.assertNumQueries(2):
+            retrieved_employee = SelfDirectedEmployee.objects.prefetch_related(
+                Prefetch("boss", SelfDirectedEmployee.objects.all())
+            ).get()
+        with self.assertNumQueries(0):
+            self.assertEqual(retrieved_employee, employee)
+            self.assertEqual(retrieved_employee.boss, retrieved_employee)
+
 
 class RawQuerySetTests(TestDataMixin, TestCase):
     def test_basic(self):