Fixed #21846 -- Made NestedObjects handle related_name with %(app_label)s or %(class)s.

django/contrib/admin/utils.py

@@ -156,10 +156,14 @@ class NestedObjects(Collector):
     def add_edge(self, source, target):
         self.edges.setdefault(source, []).append(target)
 
-    def collect(self, objs, source_attr=None, **kwargs):
+    def collect(self, objs, source=None, source_attr=None, **kwargs):
         for obj in objs:
             if source_attr:
-                self.add_edge(getattr(obj, source_attr), obj)
+                related_name = source_attr % {
+                    'class': source._meta.model_name,
+                    'app_label': source._meta.app_label,
+                }
+                self.add_edge(getattr(obj, related_name), obj)
             else:
                 self.add_edge(None, obj)
         try:

tests/admin_util/models.py

@@ -47,3 +47,18 @@ class Guest(models.Model):
 
 class EventGuide(models.Model):
     event = models.ForeignKey(Event, on_delete=models.DO_NOTHING)
+
+
+class Vehicle(models.Model):
+    pass
+
+
+class VehicleMixin(Vehicle):
+    vehicle = models.OneToOneField(Vehicle, parent_link=True, related_name='vehicle_%(app_label)s_%(class)s')
+
+    class Meta:
+        abstract = True
+
+
+class Car(VehicleMixin):
+    pass

tests/admin_util/tests.py

@@ -16,7 +16,7 @@ from django.utils.formats import localize
 from django.utils.safestring import mark_safe
 from django.utils import six
 
-from .models import Article, Count, Event, Location, EventGuide
+from .models import Article, Count, Event, Location, EventGuide, Vehicle, Car
 
 
 class NestedObjectsTests(TestCase):
@@ -80,6 +80,16 @@ class NestedObjectsTests(TestCase):
             # One for Location, one for Guest, and no query for EventGuide
             n.collect(objs)
 
+    def test_relation_on_abstract(self):
+        """
+        #21846 -- Check that `NestedObjects.collect()` doesn't trip
+        (AttributeError) on the special notation for relations on abstract
+        models (related_name that contains %(app_label)s and/or %(class)s).
+        """
+        n = NestedObjects(using=DEFAULT_DB_ALIAS)
+        Car.objects.create()
+        n.collect([Vehicle.objects.first()])
+
 
 class UtilTests(SimpleTestCase):
     def test_values_from_lookup_field(self):