Update page draft_title immediately when title segment is edited

wagtail_localize/models.py

@@ -18,9 +18,11 @@
     Subquery,
     Exists,
     OuterRef,
-    Q
+    Q,
+    F
 )
-from django.db.models.signals import post_delete
+from django.db.models.signals import post_delete, post_save
+from django.dispatch import receiver
 from django.utils import timezone
 from django.utils.encoding import force_text
 from django.utils.text import capfirst, slugify
@@ -1050,6 +1052,28 @@ def get_comment(self):
             return _("Machine translated on {date}").format(date=self.updated_at.strftime(DATE_FORMAT))
 
 
+@receiver(post_save, sender=StringTranslation)
+def post_save_string_translation(instance, **kwargs):
+    # If the StringTranslation is for a page title, update that page's draft_title field
+    if instance.context.path == 'title':
+        # Note: if this StringTranslation isn't for a page, this should do nothing
+        Page.objects.filter(
+            translation_key=instance.context.object_id,
+            locale_id=instance.locale_id
+        ).update(draft_title=instance.data)
+
+
+@receiver(post_delete, sender=StringTranslation)
+def post_delete_string_translation(instance, **kwargs):
+    # If the StringTranslation is for a page title, reset that page's draft title to the main title
+    if instance.context.path == 'title':
+        # Note: if this StringTranslation isn't for a page, this should do nothing
+        Page.objects.filter(
+            translation_key=instance.context.object_id,
+            locale_id=instance.locale_id
+        ).update(draft_title=F('title'))
+
+
 class Template(models.Model):
     BASE_UUID_NAMESPACE = uuid.UUID("4599eabc-3f8e-41a9-be61-95417d26a8cd")
 

wagtail_localize/static_src/editor/components/TranslationEditor/header.tsx

@@ -111,7 +111,8 @@ const EditorHeader: FunctionComponent<EditorHeaderProps> = ({
     breadcrumb,
     sourceLocale,
     locale,
-    translations
+    translations,
+    stringTranslations
 }) => {
     // Build actions
     let actions = [];
@@ -162,9 +163,22 @@ const EditorHeader: FunctionComponent<EditorHeaderProps> = ({
         />
     ];
 
+    // Title
+    // Allow the title to be overridden by the segment that represents the "title" field on Pages.
+    let title = object.title;
+    if (object.titleSegmentId) {
+        Array.from(stringTranslations.entries()).forEach(
+            ([segmentId, stringTranslation]) => {
+                if (segmentId == object.titleSegmentId) {
+                    title = stringTranslation.value;
+                }
+            }
+        );
+    }
+
     return (
         <Header
-            title={object.title}
+            title={title}
             breadcrumb={breadcrumb}
             actions={actions}
             meta={meta}

wagtail_localize/static_src/editor/components/TranslationEditor/index.tsx

@@ -113,6 +113,7 @@ export interface EditorProps {
     csrfToken: string;
     object: {
         title: string;
+        titleSegmentId: number | null;
         isLive: boolean;
         isLocked: boolean;
         lastPublishedDate: string | null;

wagtail_localize/views/edit_translation.py

@@ -358,6 +358,7 @@ def edit_translation(request, translation, instance):
     tab_helper = TabHelper(source_instance)
 
     breadcrumb = []
+    title_segment_id = None
     if isinstance(instance, Page):
         # find the closest common ancestor of the pages that this user has direct explore permission
         # (i.e. add/edit/publish/lock) over; this will be the root of the breadcrumb
@@ -373,6 +374,13 @@ def edit_translation(request, translation, instance):
                 for page in instance.get_ancestors(inclusive=False).descendant_of(cca, inclusive=True)
             ]
 
+        # Set to the ID of a string segment that represents the title.
+        # If this segment has a translation, the title will be replaced with that translation.
+        try:
+            title_segment_id = string_segments.get(context__path='title').id
+        except StringSegment.DoesNotExist:
+            pass
+
     machine_translator = None
     translator = get_machine_translator()
     if translator and translator.can_translate(translation.source.locale, translation.target_locale):
@@ -414,6 +422,7 @@ def edit_translation(request, translation, instance):
         'props': json.dumps({
             'object': {
                 'title': str(instance),
+                'titleSegmentId': title_segment_id,
                 'isLive': is_live,
                 'isLocked': is_locked,
                 'lastPublishedDate': last_published_at.strftime('%-d %B %Y') if last_published_at is not None else None,