From a2aea4521d5e3cf8c76ef17e6edafee1c87bbf0a Mon Sep 17 00:00:00 2001
From: Morgan Wahl <morgan@addgene.org>
Date: Tue, 5 Dec 2017 16:08:50 -0500
Subject: [PATCH] [1.11.x] Refs #28856 -- Fixed caching of a GenericForeignKey
 pointing to a model that uses more than one level of MTI.

---
 docs/releases/1.11.9.txt                  |  3 +++
 tests/generic_relations_regress/models.py |  5 +++++
 tests/generic_relations_regress/tests.py  | 12 +++++++++---
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/docs/releases/1.11.9.txt b/docs/releases/1.11.9.txt
index fa480d44bca..b8021ce70d7 100644
--- a/docs/releases/1.11.9.txt
+++ b/docs/releases/1.11.9.txt
@@ -17,3 +17,6 @@ Bugfixes
 
 * Fixed incorrect foreign key constraint name for models with quoted
   ``db_table`` (:ticket:`28876`).
+* Fixed a regression in caching of a ``GenericForeignKey`` when the referenced
+  model instance uses more than one level of multi-table inheritance
+  (:ticket:`28856`).
diff --git a/tests/generic_relations_regress/models.py b/tests/generic_relations_regress/models.py
index 2011ea14b9a..c9572eb9618 100644
--- a/tests/generic_relations_regress/models.py
+++ b/tests/generic_relations_regress/models.py
@@ -38,6 +38,11 @@ class Restaurant(Place):
         return "Restaurant: %s" % self.name
 
 
+class Cafe(Restaurant):
+    def __str__(self):
+        return "Cafe: %s" % self.name
+
+
 class Address(models.Model):
     street = models.CharField(max_length=80)
     city = models.CharField(max_length=50)
diff --git a/tests/generic_relations_regress/tests.py b/tests/generic_relations_regress/tests.py
index cfac484053a..f052cb61dfb 100644
--- a/tests/generic_relations_regress/tests.py
+++ b/tests/generic_relations_regress/tests.py
@@ -5,9 +5,10 @@ from django.forms.models import modelform_factory
 from django.test import TestCase, skipIfDBFeature
 
 from .models import (
-    A, Address, B, Board, C, CharLink, Company, Contact, Content, D, Developer,
-    Guild, HasLinkThing, Link, Node, Note, OddRelation1, OddRelation2,
-    Organization, Person, Place, Related, Restaurant, Tag, Team, TextLink,
+    A, Address, B, Board, C, Cafe, CharLink, Company, Contact, Content, D,
+    Developer, Guild, HasLinkThing, Link, Node, Note, OddRelation1,
+    OddRelation2, Organization, Person, Place, Related, Restaurant, Tag, Team,
+    TextLink,
 )
 
 
@@ -54,6 +55,11 @@ class GenericRelationTests(TestCase):
         charlink = CharLink.objects.latest('pk')
         self.assertIs(charlink.content_object, charlink.content_object)
 
+        cafe = Cafe.objects.create()
+        CharLink.objects.create(content_object=cafe)
+        charlink = CharLink.objects.latest('pk')
+        self.assertIs(charlink.content_object, charlink.content_object)
+
     def test_q_object_or(self):
         """
         SQL query parameters for generic relations are properly