Fixed Django 1.4 compatibility. Thanks to bloodchild for the report!

haystack/admin.py

@@ -12,13 +12,13 @@
     from django.contrib.admin.options import csrf_protect_m
 except ImportError:
     from haystack.utils.decorators import method_decorator
-    
+
     # Do nothing on Django 1.1 and below.
     def csrf_protect(view):
         def wraps(request, *args, **kwargs):
             return view(request, *args, **kwargs)
         return wraps
-    
+
     csrf_protect_m = method_decorator(csrf_protect)
 
 def list_max_show_all(changelist):
@@ -39,18 +39,18 @@ class SearchChangeList(ChangeList):
     def get_results(self, request):
         if not SEARCH_VAR in request.GET:
             return super(SearchChangeList, self).get_results(request)
-        
+
         # Note that pagination is 0-based, not 1-based.
         sqs = SearchQuerySet().models(self.model).auto_query(request.GET[SEARCH_VAR]).load_all()
-        
+
         paginator = Paginator(sqs, self.list_per_page)
         # Get the number of objects, with admin filters applied.
         result_count = paginator.count
         full_result_count = SearchQuerySet().models(self.model).all().count()
-        
+
         can_show_all = result_count <= list_max_show_all(self)
         multi_page = result_count > self.list_per_page
-        
+
         # Get the list of objects to display on this page.
         try:
             result_list = paginator.page(self.page_num+1).object_list
@@ -59,7 +59,7 @@ def get_results(self, request):
             result_list = [result.object for result in result_list]
         except InvalidPage:
             result_list = ()
-        
+
         self.result_count = result_count
         self.full_result_count = full_result_count
         self.result_list = result_list
@@ -73,26 +73,44 @@ class SearchModelAdmin(ModelAdmin):
     def changelist_view(self, request, extra_context=None):
         if not self.has_change_permission(request, None):
             raise PermissionDenied
-        
+
         if not SEARCH_VAR in request.GET:
             # Do the usual song and dance.
             return super(SearchModelAdmin, self).changelist_view(request, extra_context)
-        
+
         # Do a search of just this model and populate a Changelist with the
         # returned bits.
         if not self.model in connections['default'].get_unified_index().get_indexed_models():
             # Oops. That model isn't being indexed. Return the usual
             # behavior instead.
             return super(SearchModelAdmin, self).changelist_view(request, extra_context)
-        
+
         # So. Much. Boilerplate.
         # Why copy-paste a few lines when you can copy-paste TONS of lines?
         list_display = list(self.list_display)
-
-        changelist = SearchChangeList(request, self.model, list_display, self.list_display_links, self.list_filter, self.date_hierarchy, self.search_fields, self.list_select_related, self.list_per_page, self.list_editable, self)
+
+        kwargs = {
+            'request': request,
+            'model': self.model,
+            'list_display': list_display,
+            'list_display_links': self.list_display_links,
+            'list_filter': self.list_filter,
+            'date_hierarchy': self.date_hierarchy,
+            'search_fields': self.search_fields,
+            'list_select_related': self.list_select_related,
+            'list_per_page': self.list_per_page,
+            'list_editable': self.list_editable,
+            'model_admin': self
+        }
+
+        # Django 1.4 compatibility.
+        if hasattr(self, 'list_max_show_all'):
+            kwargs['list_max_show_all'] = self.list_max_show_all
+
+        changelist = SearchChangeList(**kwargs)
         formset = changelist.formset = None
         media = self.media
-        
+
         # Build the action form and populate it with available actions.
         # Check actions to see if any are available on this changelist
         actions = self.get_actions(request)
@@ -101,12 +119,12 @@ def changelist_view(self, request, extra_context=None):
             action_form.fields['action'].choices = self.get_action_choices(request)
         else:
             action_form = None
-        
+
         selection_note = ungettext('0 of %(count)d selected',
             'of %(count)d selected', len(changelist.result_list))
         selection_note_all = ungettext('%(total_count)s selected',
             'All %(total_count)s selected', changelist.result_count)
-        
+
         context = {
             'module_name': force_unicode(self.model._meta.verbose_name_plural),
             'selection_note': selection_note % {'count': len(changelist.result_list)},
@@ -116,7 +134,8 @@ def changelist_view(self, request, extra_context=None):
             'cl': changelist,
             'media': media,
             'has_add_permission': self.has_add_permission(request),
-            'root_path': self.admin_site.root_path,
+            # More Django 1.4 compatibility
+            'root_path': getattr(self.admin_site, 'root_path', None),
             'app_label': self.model._meta.app_label,
             'action_form': action_form,
             'actions_on_top': self.actions_on_top,
@@ -130,4 +149,4 @@ def changelist_view(self, request, extra_context=None):
             'admin/%s/change_list.html' % self.model._meta.app_label,
             'admin/change_list.html'
         ], context, context_instance=context_instance)
-            
+