[Bug 1269104] Compare a new translation to the English document

kuma/wiki/views/list.py

@@ -8,9 +8,8 @@
 
 from ..constants import DOCUMENTS_PER_PAGE
 from ..decorators import process_document_path, prevent_indexing
-from ..models import (Document, DocumentTag, Revision, ReviewTag,
+from ..models import (Document, DocumentTag, ReviewTag,
                       LocalizationTag)
-from ..queries import MultiQuerySet
 
 
 @block_user_agents
@@ -190,30 +189,28 @@ def get_previous(revisions):
 
     # Grab revisions, but defer summary and content because they can lead to
     # attempts to cache more than memcached allows.
-    revisions = MultiQuerySet(
-        (Revision.objects.filter(pk=document.current_revision.pk)
-                         .prefetch_related('creator', 'document')
-                         .transform(get_previous)),
-        (Revision.objects.filter(document=document)
-                         .order_by('-created', '-id')
-                         .exclude(pk=document.current_revision.pk)
-                         .prefetch_related('creator', 'document')
-                         .transform(get_previous))
-    )
-
-    if not revisions.exists():
+    all_revisions = (document.revisions.defer('summary', 'content').order_by('created', 'id')
+                                                                   .reverse().transform(get_previous))
+
+    if not all_revisions.exists():
         raise Http404
 
     if per_page == 'all':
         page = None
+        revisions = list(all_revisions)
     else:
         try:
             per_page = int(per_page)
         except ValueError:
             per_page = DOCUMENTS_PER_PAGE
 
-        page = paginate(request, revisions, per_page)
-        revisions = page.object_list
+        page = paginate(request, all_revisions, per_page)
+        revisions = list(page.object_list)
+    # In order to compare the first revision of a translation, need to insert its parent revision to the list
+    # The parent revision should stay at last page in order to compare. So insert only if there are no next page or
+    # all revisions are showing
+    if (not page or not page.has_next()) and document.parent:
+        revisions.append(all_revisions.last().based_on)
 
     context = {
         'revisions': revisions,

kuma/wiki/views/revision.py

@@ -94,7 +94,12 @@ def compare(request, document_slug, document_locale):
     to_id = smart_int(request.GET.get('to'))
 
     revisions = Revision.objects.prefetch_related('document')
-    revision_from = get_object_or_404(revisions, id=from_id, document=doc)
+    # It should also be possible to compare from the parent document revision
+    try:
+        revision_from = revisions.get(id=from_id, document=doc)
+    except Revision.DoesNotExist:
+        revision_from = get_object_or_404(revisions, id=from_id, document=doc.parent)
+
     revision_to = get_object_or_404(revisions, id=to_id, document=doc)
 
     context = {