Fixed #33450 -- Fixed RelatedExact lookups for GenericRelation and GenericRel with custom primary key types.

django/contrib/contenttypes/fields.py

@@ -288,6 +288,13 @@ class GenericRel(ForeignObjectRel):
             on_delete=DO_NOTHING,
         )
 
+    def get_effective_target_field(self):
+        """
+        Return the field used to prepare lookup values when this relation is
+        the target of a related exact lookup.
+        """
+        return self.path_infos[0].from_opts.pk
+
 
 class GenericRelation(ForeignObject):
     """
@@ -483,6 +490,13 @@ class GenericRelation(ForeignObject):
         qs = getattr(obj, self.name).all()
         return str([instance.pk for instance in qs])
 
+    def get_effective_target_field(self):
+        """
+        Return the field used to prepare lookup values when this relation is
+        the target of a related exact lookup.
+        """
+        return self.path_infos[0].from_opts.pk
+
     def contribute_to_class(self, cls, name, **kwargs):
         kwargs["private_only"] = True
         super().contribute_to_class(cls, name, **kwargs)

django/db/models/fields/related_lookups.py

@@ -106,9 +106,16 @@ class RelatedLookupMixin:
             # doesn't have validation for non-integers, so we must run validation
             # using the target field.
             if self.prepare_rhs and hasattr(self.lhs.output_field, "path_infos"):
-                # Get the target field. We can safely assume there is only one
-                # as we don't get to the direct value branch otherwise.
-                target_field = self.lhs.output_field.path_infos[-1].target_fields[-1]
+                if hasattr(self.lhs.output_field, "get_effective_target_field"):
+                    # If the output_field specifies a field to prepare the rhs with,
+                    # use it.
+                    target_field = self.lhs.output_field.get_effective_target_field()
+                else:
+                    # Get the target field. We can safely assume there is only one
+                    # as we don't get to the direct value branch otherwise.
+                    target_field = self.lhs.output_field.path_infos[-1].target_fields[
+                        -1
+                    ]
                 self.rhs = target_field.get_prep_value(self.rhs)
 
         return super().get_prep_lookup()

django/db/models/lookups.py

@@ -255,8 +255,12 @@ class FieldGetDbPrepValueMixin:
 
     def get_db_prep_lookup(self, value, connection):
         # For relational fields, use the 'target_field' attribute of the
-        # output_field.
-        field = getattr(self.lhs.output_field, "target_field", None)
+        # output_field. If the field provides a get_effective_target_field
+        # method, use that.
+        if hasattr(self.lhs.output_field, "get_effective_target_field"):
+            field = self.lhs.output_field.get_effective_target_field()
+        else:
+            field = getattr(self.lhs.output_field, "target_field", None)
         get_db_prep_value = (
             getattr(field, "get_db_prep_value", None)
             or self.lhs.output_field.get_db_prep_value

tests/generic_relations/models.py

@@ -150,3 +150,25 @@ class AllowsNullGFK(models.Model):
     content_type = models.ForeignKey(ContentType, models.SET_NULL, null=True)
     object_id = models.PositiveIntegerField(null=True)
     content_object = GenericForeignKey()
+
+
+class Note(models.Model):
+    title = models.CharField(max_length=30)
+    content_type = models.ForeignKey(
+        ContentType, on_delete=models.CASCADE, related_name="notes"
+    )
+    object_id = models.CharField(max_length=36)
+    owner = GenericForeignKey()
+
+
+class Story(models.Model):
+    name = models.CharField(max_length=30, primary_key=True)
+    notes = GenericRelation("Note", related_query_name="story")
+    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE, null=True)
+    object_id = models.PositiveIntegerField(null=True)
+    inspiration = GenericForeignKey()
+
+
+class Idea(models.Model):
+    description = models.TextField()
+    stories = GenericRelation(Story)

tests/generic_relations/tests.py

@@ -13,10 +13,13 @@ from .models import (
     ForConcreteModelModel,
     ForProxyModelModel,
     Gecko,
+    Idea,
     ManualPK,
     Mineral,
+    Note,
     ProxyRelatedModel,
     Rock,
+    Story,
     TaggedItem,
     ValuableRock,
     ValuableTaggedItem,
@@ -860,3 +863,17 @@ class TestInitWithNoneArgument(SimpleTestCase):
         # TaggedItem requires a content_type but initializing with None should
         # be allowed.
         TaggedItem(content_object=None)
+
+
+class GenericRelationQueryTests(TestCase):
+    def test_generic_relation_related_exact_lookup_incompatible_pk_types(self):
+        story = Story.objects.create(name="The Hobbit")
+        note1 = Note.objects.create(title="Fantastic fantasy", owner=story)
+        self.assertSequenceEqual(Note.objects.filter(story=story), [note1])
+        self.assertSequenceEqual(Note.objects.filter(story=story.pk), [note1])
+
+    def test_generic_relation_reverse_related_exact_lookup_incompatible_pk_types(self):
+        idea = Idea.objects.create(description="Eureka")
+        story = Story.objects.create(name="Bathtime Serendipity", inspiration=idea)
+        self.assertSequenceEqual(Idea.objects.filter(stories=story), [idea])
+        self.assertSequenceEqual(Idea.objects.filter(stories=story.pk), [idea])