Fixed #19951 -- Admin: Invalid model PK values shouldn't cause 500 status.

Avoid ValueError in admin when passing a string as PK for an inherited
model with an integer PK field.

Thanks ikks for the patch. See also #11191.

django/contrib/admin/options.py

@@ -501,7 +501,7 @@ class ModelAdmin(BaseModelAdmin):
         try:
             object_id = model._meta.pk.to_python(object_id)
             return queryset.get(pk=object_id)
-        except (model.DoesNotExist, ValidationError):
+        except (model.DoesNotExist, ValidationError, ValueError):
             return None
 
     def get_changelist_form(self, request, **kwargs):

tests/admin_views/tests.py

@@ -124,13 +124,22 @@ class AdminViewBasicTest(TestCase):
 
     def testBasicEditGetStringPK(self):
         """
-        A smoke test to ensure GET on the change_view works (returns an HTTP
-        404 error, see #11191) when passing a string as the PK argument for a
-        model with an integer PK field.
+        Ensure GET on the change_view works (returns an HTTP 404 error, see
+        #11191) when passing a string as the PK argument for a model with an
+        integer PK field.
         """
         response = self.client.get('/test_admin/%s/admin_views/section/abc/' % self.urlbit)
         self.assertEqual(response.status_code, 404)
 
+    def testBasicInheritanceGetStringPK(self):
+        """
+        Ensure GET on the change_view works on inherited models (returns an
+        HTTP 404 error, see #19951) when passing a string as the PK argument
+        for a model with an integer PK field.
+        """
+        response = self.client.get('/test_admin/%s/admin_views/supervillain/abc/' % self.urlbit)
+        self.assertEqual(response.status_code, 404)
+
     def testBasicAddPost(self):
         """
         A smoke test to ensure POST on add_view works.