From 0e16c3e3cd61b119e067b369f3ff928a2e4045b4 Mon Sep 17 00:00:00 2001
From: Gabe Jackson <gabejackson@cxg.ch>
Date: Tue, 2 Sep 2014 15:30:53 +0200
Subject: [PATCH] Fixed #23396 -- Ensured ValueQuerySets are not checked by
 check_related_objects.

---
 django/db/models/query.py     | 16 ++++++++++++++++
 django/db/models/sql/query.py | 26 +++++++++++---------------
 tests/queries/tests.py        |  8 ++++++++
 3 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/django/db/models/query.py b/django/db/models/query.py
index 85f1981662..d35f54b0b5 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -1052,6 +1052,15 @@ class QuerySet(object):
         """
         return self.query.has_filters()
 
+    def is_compatible_query_object_type(self, opts):
+        model = self.model
+        return (
+            model == opts.concrete_model or
+            opts.concrete_model in model._meta.get_parent_list() or
+            model in opts.get_parent_list()
+        )
+    is_compatible_query_object_type.queryset_only = True
+
 
 class InstanceCheckMeta(type):
     def __instancecheck__(self, instance):
@@ -1209,6 +1218,13 @@ class ValuesQuerySet(QuerySet):
                     % self.__class__.__name__)
         return self
 
+    def is_compatible_query_object_type(self, opts):
+        """
+        ValueQuerySets do not need to be checked for compatibility.
+        We trust that users of ValueQuerySets know what they are doing.
+        """
+        return True
+
 
 class ValuesListQuerySet(ValuesQuerySet):
     def iterator(self):
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 2e7b37d423..08af1fb008 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -1094,21 +1094,17 @@ class Query(object):
         Checks the type of object passed to query relations.
         """
         if field.rel:
-            # testing for iterable of models
-            if hasattr(value, '__iter__'):
-                # Check if the iterable has a model attribute, if so
-                # it is likely something like a QuerySet.
-                if hasattr(value, 'model') and hasattr(value.model, '_meta'):
-                    model = value.model
-                    if not (model == opts.concrete_model
-                            or opts.concrete_model in model._meta.get_parent_list()
-                            or model in opts.get_parent_list()):
-                        raise ValueError(
-                            'Cannot use QuerySet for "%s": Use a QuerySet for "%s".' %
-                            (model._meta.model_name, opts.object_name))
-                else:
-                    for v in value:
-                        self.check_query_object_type(v, opts)
+            # QuerySets implement is_compatible_query_object_type() to
+            # determine compatibility with the given field.
+            if hasattr(value, 'is_compatible_query_object_type'):
+                if not value.is_compatible_query_object_type(opts):
+                    raise ValueError(
+                        'Cannot use QuerySet for "%s": Use a QuerySet for "%s".' %
+                        (value.model._meta.model_name, opts.object_name)
+                    )
+            elif hasattr(value, '__iter__'):
+                for v in value:
+                    self.check_query_object_type(v, opts)
             else:
                 # expecting single model instance here
                 self.check_query_object_type(value, opts)
diff --git a/tests/queries/tests.py b/tests/queries/tests.py
index d6f7aa38a0..8ec3fd5945 100644
--- a/tests/queries/tests.py
+++ b/tests/queries/tests.py
@@ -3487,6 +3487,14 @@ class RelatedLookupTypeTests(TestCase):
         with self.assertNumQueries(0):
             ObjectB.objects.filter(objecta__in=ObjectA.objects.all())
 
+    def test_values_queryset_lookup(self):
+        """
+        #23396 - Ensure ValueQuerySets are not checked for compatibility with the lookup field
+        """
+        self.assertQuerysetEqual(ObjectB.objects.filter(
+            objecta__in=ObjectB.objects.all().values_list('pk')
+        ).order_by('pk'), ['<ObjectB: ob>', '<ObjectB: pob>'])
+
 
 class Ticket14056Tests(TestCase):
     def test_ticket_14056(self):