From c8152137400b5932578cd1788b79560c9772e56b Mon Sep 17 00:00:00 2001
From: Mariusz Felisiak <felisiak.mariusz@gmail.com>
Date: Wed, 27 Dec 2017 18:38:30 +0100
Subject: [PATCH] Fixed #28958 -- Fixed admin changelist crash when using a
 query expression in the page's ordering.

Thanks Tim Graham for the review.
---
 django/contrib/admin/views/main.py |  9 ++++++++-
 docs/releases/2.0.1.txt            |  3 +++
 tests/admin_changelist/tests.py    | 16 ++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/django/contrib/admin/views/main.py b/django/contrib/admin/views/main.py
index 2d13593b30..263f4ac148 100644
--- a/django/contrib/admin/views/main.py
+++ b/django/contrib/admin/views/main.py
@@ -15,6 +15,7 @@ from django.core.exceptions import (
 )
 from django.core.paginator import InvalidPage
 from django.db import models
+from django.db.models.expressions import F, OrderBy
 from django.urls import reverse
 from django.utils.http import urlencode
 from django.utils.translation import gettext
@@ -287,7 +288,13 @@ class ChangeList:
             # the right column numbers absolutely, because there might be more
             # than one column associated with that ordering, so we guess.
             for field in ordering:
-                if field.startswith('-'):
+                if isinstance(field, OrderBy):
+                    if isinstance(field.expression, F):
+                        order_type = 'desc' if field.descending else 'asc'
+                        field = field.expression.name
+                    else:
+                        continue
+                elif field.startswith('-'):
                     field = field[1:]
                     order_type = 'desc'
                 else:
diff --git a/docs/releases/2.0.1.txt b/docs/releases/2.0.1.txt
index 97260ef5b8..0c3a571913 100644
--- a/docs/releases/2.0.1.txt
+++ b/docs/releases/2.0.1.txt
@@ -40,3 +40,6 @@ Bugfixes
 
 * Fixed a crash when chaining ``values()`` or ``values_list()`` after
   ``QuerySet.select_for_update(of=(...))`` (:ticket:`28944`).
+
+* Fixed admin changelist crash when using a query expression in the page's
+  ordering (:ticket:`28958`).
diff --git a/tests/admin_changelist/tests.py b/tests/admin_changelist/tests.py
index 537949021f..5f3d30fd68 100644
--- a/tests/admin_changelist/tests.py
+++ b/tests/admin_changelist/tests.py
@@ -8,7 +8,9 @@ from django.contrib.admin.tests import AdminSeleniumTestCase
 from django.contrib.admin.views.main import ALL_VAR, SEARCH_VAR
 from django.contrib.auth.models import User
 from django.contrib.contenttypes.models import ContentType
+from django.db.models import F
 from django.db.models.fields import Field, IntegerField
+from django.db.models.functions import Upper
 from django.db.models.lookups import Contains, Exact
 from django.template import Context, Template
 from django.test import TestCase, override_settings
@@ -57,6 +59,20 @@ class ChangeListTests(TestCase):
         request.user = user
         return request
 
+    def test_specified_ordering_by_f_expression(self):
+        class OrderedByFBandAdmin(admin.ModelAdmin):
+            list_display = ['name', 'genres', 'nr_of_members']
+            ordering = (
+                F('nr_of_members').desc(nulls_last=True),
+                Upper(F('name')).asc(),
+                F('genres').asc(),
+            )
+
+        m = OrderedByFBandAdmin(Band, custom_site)
+        request = self.factory.get('/band/')
+        cl = m.get_changelist_instance(request)
+        self.assertEqual(cl.get_ordering_field_columns(), {3: 'desc', 2: 'asc'})
+
     def test_select_related_preserved(self):
         """
         Regression test for #10348: ChangeList.get_queryset() shouldn't