Fixed #21204 -- Tracked field deferrals by field instead of models.

This ensures field deferral works properly when a model is involved
more than once in the same query with a distinct deferral mask.

3 files changed, 26 insertions, 8 deletions

diff --git a/tests/defer/tests.py b/tests/defer/tests.py
index fe9637c7f1..c2319b54ec 100644
--- a/tests/defer/tests.py
+++ b/tests/defer/tests.py
@@ -290,6 +290,8 @@ class InvalidDeferTests(SimpleTestCase):
         msg = "Primary has no field named 'missing'"
         with self.assertRaisesMessage(FieldDoesNotExist, msg):
             list(Primary.objects.defer("missing"))
+        with self.assertRaisesMessage(FieldError, "missing"):
+            list(Primary.objects.defer("value__missing"))
         msg = "Secondary has no field named 'missing'"
         with self.assertRaisesMessage(FieldDoesNotExist, msg):
             list(Primary.objects.defer("related__missing"))
@@ -298,6 +300,8 @@ class InvalidDeferTests(SimpleTestCase):
         msg = "Primary has no field named 'missing'"
         with self.assertRaisesMessage(FieldDoesNotExist, msg):
             list(Primary.objects.only("missing"))
+        with self.assertRaisesMessage(FieldError, "missing"):
+            list(Primary.objects.only("value__missing"))
         msg = "Secondary has no field named 'missing'"
         with self.assertRaisesMessage(FieldDoesNotExist, msg):
             list(Primary.objects.only("related__missing"))
diff --git a/tests/defer_regress/tests.py b/tests/defer_regress/tests.py
index c7a61f53a3..fb9dcdb297 100644
--- a/tests/defer_regress/tests.py
+++ b/tests/defer_regress/tests.py
@@ -246,8 +246,6 @@ class DeferRegressionTest(TestCase):
         )
         self.assertEqual(len(qs), 1)
 
-
-class DeferAnnotateSelectRelatedTest(TestCase):
     def test_defer_annotate_select_related(self):
         location = Location.objects.create()
         Request.objects.create(location=location)
@@ -276,6 +274,28 @@ class DeferAnnotateSelectRelatedTest(TestCase):
             list,
         )
 
+    def test_common_model_different_mask(self):
+        child = Child.objects.create(name="Child", value=42)
+        second_child = Child.objects.create(name="Second", value=64)
+        Leaf.objects.create(child=child, second_child=second_child)
+        with self.assertNumQueries(1):
+            leaf = (
+                Leaf.objects.select_related("child", "second_child")
+                .defer("child__name", "second_child__value")
+                .get()
+            )
+            self.assertEqual(leaf.child, child)
+            self.assertEqual(leaf.second_child, second_child)
+        self.assertEqual(leaf.child.get_deferred_fields(), {"name"})
+        self.assertEqual(leaf.second_child.get_deferred_fields(), {"value"})
+        with self.assertNumQueries(0):
+            self.assertEqual(leaf.child.value, 42)
+            self.assertEqual(leaf.second_child.name, "Second")
+        with self.assertNumQueries(1):
+            self.assertEqual(leaf.child.name, "Child")
+        with self.assertNumQueries(1):
+            self.assertEqual(leaf.second_child.value, 64)
+
 
 class DeferDeletionSignalsTests(TestCase):
     senders = [Item, Proxy]
diff --git a/tests/queries/tests.py b/tests/queries/tests.py
index 1238f021be..1bd72dd8b8 100644
--- a/tests/queries/tests.py
+++ b/tests/queries/tests.py
@@ -3594,12 +3594,6 @@ class WhereNodeTest(SimpleTestCase):
 
 
 class QuerySetExceptionTests(SimpleTestCase):
-    def test_iter_exceptions(self):
-        qs = ExtraInfo.objects.only("author")
-        msg = "'ManyToOneRel' object has no attribute 'attname'"
-        with self.assertRaisesMessage(AttributeError, msg):
-            list(qs)
-
     def test_invalid_order_by(self):
         msg = "Cannot resolve keyword '*' into field. Choices are: created, id, name"
         with self.assertRaisesMessage(FieldError, msg):