Fixed #26060 -- Fixed crash with reverse OneToOneField in ModelAdmin.readonly_fields.

tests/admin_views/tests.py

@@ -67,6 +67,43 @@ ERROR_MESSAGE = "Please enter the correct username and password \
 for a staff account. Note that both fields may be case-sensitive."
 
 
+class AdminFieldExtractionMixin(object):
+    """
+    Helper methods for extracting data from AdminForm.
+    """
+    def get_admin_form_fields(self, response):
+        """
+        Return a list of AdminFields for the AdminForm in the response.
+        """
+        admin_form = response.context['adminform']
+        fieldsets = list(admin_form)
+
+        field_lines = []
+        for fieldset in fieldsets:
+            field_lines += list(fieldset)
+
+        fields = []
+        for field_line in field_lines:
+            fields += list(field_line)
+
+        return fields
+
+    def get_admin_readonly_fields(self, response):
+        """
+        Return the readonly fields for the response's AdminForm.
+        """
+        return [f for f in self.get_admin_form_fields(response) if f.is_readonly]
+
+    def get_admin_readonly_field(self, response, field_name):
+        """
+        Return the readonly field for the given field_name.
+        """
+        admin_readonly_fields = self.get_admin_readonly_fields(response)
+        for field in admin_readonly_fields:
+            if field.field['name'] == field_name:
+                return field
+
+
 @override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.SHA1PasswordHasher'],
                    ROOT_URLCONF="admin_views.urls",
                    USE_I18N=True, USE_L10N=False, LANGUAGE_CODE='en')
@@ -4556,7 +4593,7 @@ class SeleniumAdminViewsIETests(SeleniumAdminViewsFirefoxTests):
 
 @override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.SHA1PasswordHasher'],
     ROOT_URLCONF="admin_views.urls")
-class ReadonlyTest(TestCase):
+class ReadonlyTest(AdminFieldExtractionMixin, TestCase):
 
     @classmethod
     def setUpTestData(cls):
@@ -4677,7 +4714,7 @@ class ReadonlyTest(TestCase):
         self.assertContains(response, '<p>No opinion</p>', html=True)
         self.assertNotContains(response, '<p>(None)</p>')
 
-    def test_readonly_backwards_ref(self):
+    def test_readonly_manytomany_backwards_ref(self):
         """
         Regression test for #16433 - backwards references for related objects
         broke if the related field is read-only due to the help_text attribute
@@ -4688,6 +4725,26 @@ class ReadonlyTest(TestCase):
         response = self.client.get(reverse('admin:admin_views_topping_add'))
         self.assertEqual(response.status_code, 200)
 
+    def test_readonly_onetoone_backwards_ref(self):
+        """
+        Can reference a reverse OneToOneField in ModelAdmin.readonly_fields.
+        """
+        v1 = Villain.objects.create(name='Adam')
+        pl = Plot.objects.create(name='Test Plot', team_leader=v1, contact=v1)
+        pd = PlotDetails.objects.create(details='Brand New Plot', plot=pl)
+
+        response = self.client.get(reverse('admin:admin_views_plotproxy_change', args=(pl.pk,)))
+        field = self.get_admin_readonly_field(response, 'plotdetails')
+        self.assertEqual(field.contents(), 'Brand New Plot')
+
+        # The reverse relation also works if the OneToOneField is null.
+        pd.plot = None
+        pd.save()
+
+        response = self.client.get(reverse('admin:admin_views_plotproxy_change', args=(pl.pk,)))
+        field = self.get_admin_readonly_field(response, 'plotdetails')
+        self.assertEqual(field.contents(), '-')  # default empty value
+
     @ignore_warnings(category=RemovedInDjango20Warning)  # for allow_tags deprecation
     def test_readonly_field_overrides(self):
         """