Fixed #20640 -- Avoided NoReverseMatch in get_deleted_objects

The default delete action resulted in a NoReverseMatch if it were to
list any Model with a ModelAdmin with `get_urls` overridden to remove
the change url.  Catching the error and not displaying the link in that
case, as was already done for models with no registered admins.

Thanks Keryn Knight for the report.

django/contrib/admin/util.py

@@ -16,7 +16,7 @@ from django.utils import timezone
 from django.utils.encoding import force_str, force_text, smart_text
 from django.utils import six
 from django.utils.translation import ungettext
-from django.core.urlresolvers import reverse
+from django.core.urlresolvers import reverse, NoReverseMatch
 
 def lookup_needs_distinct(opts, lookup_path):
     """
@@ -113,12 +113,20 @@ def get_deleted_objects(objs, opts, user, admin_site, using):
         has_admin = obj.__class__ in admin_site._registry
         opts = obj._meta
 
+        no_edit_link = '%s: %s' % (capfirst(opts.verbose_name),
+                                   force_text(obj))
+
         if has_admin:
-            admin_url = reverse('%s:%s_%s_change'
-                                % (admin_site.name,
-                                   opts.app_label,
-                                   opts.model_name),
-                                None, (quote(obj._get_pk_val()),))
+            try:
+                admin_url = reverse('%s:%s_%s_change'
+                                    % (admin_site.name,
+                                       opts.app_label,
+                                       opts.model_name),
+                                    None, (quote(obj._get_pk_val()),))
+            except NoReverseMatch:
+                # Change url doesn't exist -- don't display link to edit
+                return no_edit_link
+
             p = '%s.%s' % (opts.app_label,
                            get_permission_codename('delete', opts))
             if not user.has_perm(p):
@@ -131,8 +139,7 @@ def get_deleted_objects(objs, opts, user, admin_site, using):
         else:
             # Don't display link to edit, because it either has no
             # admin or is edited inline.
-            return '%s: %s' % (capfirst(opts.verbose_name),
-                                force_text(obj))
+            return no_edit_link
 
     to_delete = collector.nested(format_callback)
 

tests/admin_views/admin.py

@@ -29,7 +29,7 @@ from .models import (Article, Chapter, Account, Media, Child, Parent, Picture,
     Album, Question, Answer, ComplexSortedPerson, PluggableSearchPerson, PrePopulatedPostLargeSlug,
     AdminOrderedField, AdminOrderedModelMethod, AdminOrderedAdminMethod,
     AdminOrderedCallable, Report, Color2, UnorderedObject, MainPrepopulated,
-    RelatedPrepopulated, UndeletableObject, UserMessenger, Simple, Choice,
+    RelatedPrepopulated, UndeletableObject, UnchangeableObject, UserMessenger, Simple, Choice,
     ShortMessage, Telegram)
 
 
@@ -656,6 +656,13 @@ class UndeletableObjectAdmin(admin.ModelAdmin):
         return super(UndeletableObjectAdmin, self).change_view(*args, **kwargs)
 
 
+class UnchangeableObjectAdmin(admin.ModelAdmin):
+    def get_urls(self):
+        # Disable change_view, but leave other urls untouched
+        urlpatterns = super(UnchangeableObjectAdmin, self).get_urls()
+        return [p for p in urlpatterns if not p.name.endswith("_change")]
+
+
 def callable_on_unknown(obj):
     return obj.unknown
 
@@ -741,6 +748,7 @@ site.register(Report, ReportAdmin)
 site.register(MainPrepopulated, MainPrepopulatedAdmin)
 site.register(UnorderedObject, UnorderedObjectAdmin)
 site.register(UndeletableObject, UndeletableObjectAdmin)
+site.register(UnchangeableObject, UnchangeableObjectAdmin)
 
 # We intentionally register Promo and ChapterXtra1 but not Chapter nor ChapterXtra2.
 # That way we cover all four cases:

tests/admin_views/models.py

@@ -674,6 +674,12 @@ class UndeletableObject(models.Model):
     """
     name = models.CharField(max_length=255)
 
+class UnchangeableObject(models.Model):
+    """
+    Model whose change_view is disabled in admin
+    Refs #20640.
+    """
+
 class UserMessenger(models.Model):
     """
     Dummy class for testing message_user functions on ModelAdmin

tests/admin_views/tests.py

@@ -15,7 +15,6 @@ from django.core import mail
 from django.core.files import temp as tempfile
 from django.core.urlresolvers import reverse
 # Register auth models with the admin.
-from django.contrib import admin
 from django.contrib.auth import get_permission_codename
 from django.contrib.admin.helpers import ACTION_CHECKBOX_NAME
 from django.contrib.admin.models import LogEntry, DELETION
@@ -51,7 +50,7 @@ from .models import (Article, BarAccount, CustomArticle, EmptyModel, FooAccount,
     OtherStory, ComplexSortedPerson, PluggableSearchPerson, Parent, Child, AdminOrderedField,
     AdminOrderedModelMethod, AdminOrderedAdminMethod, AdminOrderedCallable,
     Report, MainPrepopulated, RelatedPrepopulated, UnorderedObject,
-    Simple, UndeletableObject, Choice, ShortMessage, Telegram)
+    Simple, UndeletableObject, UnchangeableObject, Choice, ShortMessage, Telegram)
 from .admin import site, site2
 
 
@@ -2422,6 +2421,24 @@ class AdminActionsTest(TestCase):
         self.assertContains(response, '<li>Answer: <a href="/test_admin/admin/admin_views/answer/%s/">Because.</a></li>' % a1.pk, html=True)
         self.assertContains(response, '<li>Answer: <a href="/test_admin/admin/admin_views/answer/%s/">Yes.</a></li>' % a2.pk, html=True)
 
+    def test_model_admin_default_delete_action_no_change_url(self):
+        """
+        Default delete action shouldn't break if a user's ModelAdmin removes the url for change_view.
+
+        Regression test for #20640
+        """
+        obj = UnchangeableObject.objects.create()
+        action_data = {
+            ACTION_CHECKBOX_NAME: obj.pk,
+            "action": "delete_selected",
+            "index": "0",
+        }
+        response = self.client.post('/test_admin/admin/admin_views/unchangeableobject/', action_data)
+        # No 500 caused by NoReverseMatch
+        self.assertEqual(response.status_code, 200)
+        # The page shouldn't display a link to the nonexistent change page
+        self.assertContains(response, "<li>Unchangeable object: UnchangeableObject object</li>", 1, html=True)
+
     def test_custom_function_mail_action(self):
         "Tests a custom action defined in a function"
         action_data = {