Fixed #5350 -- Added fallback to default 404/500 handlers when they're not…

Fixed #5350 -- Added fallback to default 404/500 handlers when they're not explicitly specified (or imported) in a urls.py file. Thanks to Thomas Güttler for the report and initial patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13590 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/urlresolvers.py

@@ -284,7 +284,12 @@ class RegexURLResolver(object):
     url_patterns = property(_get_url_patterns)
 
     def _resolve_special(self, view_type):
-        callback = getattr(self.urlconf_module, 'handler%s' % view_type)
+        callback = getattr(self.urlconf_module, 'handler%s' % view_type, None)
+        if not callback:
+            # No handler specified in file; use default
+            # Lazy import, since urls.defaults imports this file
+            from django.conf.urls import defaults
+            callback = getattr(defaults, 'handler%s' % view_type)
         try:
             return get_callable(callback), {}
         except (ImportError, AttributeError), e:

tests/regressiontests/urlpatterns_reverse/tests.py

@@ -356,6 +356,22 @@ class ErrorHandlerResolutionTests(TestCase):
         self.assertEqual(self.callable_resolver.resolve404(), handler)
         self.assertEqual(self.callable_resolver.resolve500(), handler)
 
+class DefaultErrorHandlerTests(TestCase):
+    urls = 'regressiontests.urlpatterns_reverse.urls_without_full_import'
+
+    def test_default_handler(self):
+        "If the urls.py doesn't specify handlers, the defaults are used"
+        try:
+            response = self.client.get('/test/')
+            self.assertEquals(response.status_code, 404)
+        except AttributeError:
+            self.fail("Shouldn't get an AttributeError due to undefined 404 handler")
+
+        try:
+            self.assertRaises(ValueError, self.client.get, '/bad_view/')
+        except AttributeError:
+            self.fail("Shouldn't get an AttributeError due to undefined 500 handler")
+
 class NoRootUrlConfTests(TestCase):
     """Tests for handler404 and handler500 if urlconf is None"""
     urls = None

tests/regressiontests/urlpatterns_reverse/views.py

+from django.http import HttpResponse
+
 def empty_view(request, *args, **kwargs):
-    pass
+    return HttpResponse('')
 
 def kwargs_view(request, arg1=1, arg2=2):
-    pass
+    return HttpResponse('')
 
 def absolute_kwargs_view(request, arg1=1, arg2=2):
-    pass
+    return HttpResponse('')
 
 class ViewClass(object):
     def __call__(self, request, *args, **kwargs):
-        pass
+        return HttpResponse('')
 
 view_class_instance = ViewClass()
+
+def bad_view(request, *args, **kwargs):
+    raise ValueError("I don't think I'm getting good value for this view")