From ec2c9c353113bb1db6e32ed3f0b6c28bc06ca2eb Mon Sep 17 00:00:00 2001
From: Tim Graham <timograham@gmail.com>
Date: Thu, 14 Jun 2018 14:47:20 -0400
Subject: [PATCH] Refs #29428 -- Fixed admin check crash when using a query
 expression in ModelAdmin.ordering.

---
 django/contrib/admin/checks.py  |  9 ++++++++-
 docs/releases/2.0.7.txt         |  3 +++
 tests/modeladmin/test_checks.py | 19 +++++++++++++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/django/contrib/admin/checks.py b/django/contrib/admin/checks.py
index e0f3a21550..cf5b312369 100644
--- a/django/contrib/admin/checks.py
+++ b/django/contrib/admin/checks.py
@@ -10,6 +10,7 @@ from django.core import checks
 from django.core.exceptions import FieldDoesNotExist
 from django.db import models
 from django.db.models.constants import LOOKUP_SEP
+from django.db.models.expressions import Combinable, F, OrderBy
 from django.forms.models import (
     BaseModelForm, BaseModelFormSet, _get_foreign_key,
 )
@@ -489,7 +490,13 @@ class BaseModelAdminChecks:
 
     def _check_ordering_item(self, obj, model, field_name, label):
         """ Check that `ordering` refers to existing fields. """
-
+        if isinstance(field_name, (Combinable, OrderBy)):
+            if not isinstance(field_name, OrderBy):
+                field_name = field_name.asc()
+            if isinstance(field_name.expression, F):
+                field_name = field_name.expression.name
+            else:
+                return []
         if field_name == '?' and len(obj.ordering) != 1:
             return [
                 checks.Error(
diff --git a/docs/releases/2.0.7.txt b/docs/releases/2.0.7.txt
index 46d6e86073..4890ee2dba 100644
--- a/docs/releases/2.0.7.txt
+++ b/docs/releases/2.0.7.txt
@@ -11,3 +11,6 @@ Bugfixes
 
 * Fixed admin changelist crash when using a query expression without ``asc()``
   or ``desc()`` in the page's ordering (:ticket:`29428`).
+
+* Fixed admin check crash when using a query expression in
+  ``ModelAdmin.ordering`` (:ticket:`29428`).
diff --git a/tests/modeladmin/test_checks.py b/tests/modeladmin/test_checks.py
index f76b78078a..5a0433deb4 100644
--- a/tests/modeladmin/test_checks.py
+++ b/tests/modeladmin/test_checks.py
@@ -3,6 +3,8 @@ from django.contrib.admin import BooleanFieldListFilter, SimpleListFilter
 from django.contrib.admin.options import VERTICAL, ModelAdmin, TabularInline
 from django.contrib.admin.sites import AdminSite
 from django.core.checks import Error
+from django.db.models import F
+from django.db.models.functions import Upper
 from django.forms.models import BaseModelFormSet
 from django.test import SimpleTestCase
 
@@ -829,6 +831,23 @@ class OrderingCheckTests(CheckTestCase):
 
         self.assertIsValid(TestModelAdmin, ValidationTestModel)
 
+    def test_invalid_expression(self):
+        class TestModelAdmin(ModelAdmin):
+            ordering = (F('nonexistent'), )
+
+        self.assertIsInvalid(
+            TestModelAdmin, ValidationTestModel,
+            "The value of 'ordering[0]' refers to 'nonexistent', which is not "
+            "an attribute of 'modeladmin.ValidationTestModel'.",
+            'admin.E033'
+        )
+
+    def test_valid_expression(self):
+        class TestModelAdmin(ModelAdmin):
+            ordering = (Upper('name'), Upper('band__name').desc())
+
+        self.assertIsValid(TestModelAdmin, ValidationTestModel)
+
 
 class ListSelectRelatedCheckTests(CheckTestCase):