Optimise logic for showing 'Translate' button on the page listing

External translation packages e.g. wagtail-localize can make use of the annotation to get the same performance benefit

wagtail/admin/views/pages/listing.py

@@ -185,6 +185,10 @@ class IndexView(generic.IndexView):
 
         return super().get(request)
 
+    @cached_property
+    def i18n_enabled(self):
+        return getattr(settings, "WAGTAIL_I18N_ENABLED", False)
+
     def get_valid_orderings(self):
         valid_orderings = super().get_valid_orderings()
 
@@ -230,6 +234,8 @@ class IndexView(generic.IndexView):
         # Annotate queryset with various states to be used later for performance optimisations
         if getattr(settings, "WAGTAIL_WORKFLOW_ENABLED", True):
             pages = pages.prefetch_workflow_states()
+        if self.i18n_enabled:
+            pages = pages.annotate_has_untranslated_locale()
 
         pages = pages.annotate_site_root_state().annotate_approved_schedule()
 
@@ -351,7 +357,6 @@ class ExplorableIndexView(IndexView):
         self.parent_page = self.parent_page.specific
         self.scheduled_page = self.parent_page.get_scheduled_revision_as_object()
 
-        self.i18n_enabled = getattr(settings, "WAGTAIL_I18N_ENABLED", False)
         if self.i18n_enabled and not self.parent_page.is_root():
             self.locale = self.parent_page.locale
             self.translations = self.get_translations()

wagtail/contrib/simple_translation/tests/test_views.py

@@ -476,7 +476,7 @@ class TestPageListing(WagtailTestUtils, TestCase):
     def test_translate_button_displayed(self):
         url = reverse("wagtailadmin_explore", args=(self.en_homepage.pk,))
         response = self.client.get(url)
-        with self.assertNumQueries(50):
+        with self.assertNumQueries(40):
             response = self.client.get(url)
 
         soup = self.get_soup(response.content)

wagtail/contrib/simple_translation/wagtail_hooks.py

@@ -48,13 +48,18 @@ def register_submit_translation_permission():
 @hooks.register("register_page_listing_more_buttons")
 def page_listing_more_buttons(page, user, next_url=None):
     if user.has_perm("simple_translation.submit_translation") and not page.is_root():
-        # If there's at least one locale that we haven't translated into yet,
-        # show "Translate this page" button
-        has_locale_to_translate_to = Locale.objects.exclude(
-            id__in=page.get_translations(inclusive=True).values_list(
-                "locale_id", flat=True
-            )
-        ).exists()
+        if hasattr(page, "_has_untranslated_locale"):
+            # `_has_untranslated_locale` may be populated by `annotate_has_untranslated_locale`
+            # on querysets as a performance optimisation
+            has_locale_to_translate_to = page._has_untranslated_locale
+        else:
+            # If there's at least one locale that we haven't translated into yet,
+            # show "Translate this page" button
+            has_locale_to_translate_to = Locale.objects.exclude(
+                id__in=page.get_translations(inclusive=True).values_list(
+                    "locale_id", flat=True
+                )
+            ).exists()
 
         if has_locale_to_translate_to:
             url = reverse("simple_translation:submit_page_translation", args=[page.id])

wagtail/query.py

@@ -12,6 +12,7 @@ from django.db.models.functions import Cast, Length, Substr
 from django.db.models.query import BaseIterable, ModelIterable
 from treebeard.mp_tree import MP_NodeQuerySet
 
+from wagtail.models.i18n import Locale
 from wagtail.models.sites import Site
 from wagtail.search.queryset import SearchableQuerySetMixin
 
@@ -508,6 +509,17 @@ class PageQuerySet(SearchableQuerySetMixin, SpecificQuerySetMixin, TreeQuerySet)
             )
         )
 
+    def annotate_has_untranslated_locale(self):
+        return self.annotate(
+            _has_untranslated_locale=Exists(
+                Locale.objects.exclude(
+                    id__in=self.model.objects.filter(
+                        translation_key=OuterRef(OuterRef("translation_key"))
+                    ).values("locale_id")
+                )
+            )
+        )
+
 
 class SpecificIterable(BaseIterable):
     def __iter__(self):