Add locale selector to add subpage view

wagtail/admin/templates/wagtailadmin/pages/create.html

@@ -15,6 +15,14 @@
                 <h1>{% trans 'New' %} <span>{{ content_type.model_class.get_verbose_name }}</span></h1>
             </div>
         </div>
+
+        {% if locale %}
+        <ul class="row header-meta">
+            <li class="header-meta--locale">
+                {% include "wagtailadmin/shared/locale_selector.html" %}
+            </li>
+        </ul>
+        {% endif %}
     </header>
 
     <form id="page-edit-form" action="{% url 'wagtailadmin_pages:add' content_type.app_label content_type.model parent_page.id %}" method="POST" novalidate{% if form.is_multipart %} enctype="multipart/form-data"{% endif %}>

wagtail/admin/tests/pages/test_create_page.py

@@ -1024,3 +1024,60 @@ class TestInlinePanelNonFieldErrors(TestCase, WagtailTestUtils):
         self.assertEqual(response.status_code, 200)
         self.assertContains(response, "The page could not be created due to validation errors")
         self.assertContains(response, 'You must provide a related page, related document or an external URL', count=1)
+
+
+@override_settings(WAGTAIL_I18N_ENABLED=True)
+class TestLocaleSelector(TestCase, WagtailTestUtils):
+    fixtures = ['test.json']
+
+    def setUp(self):
+        self.events_page = Page.objects.get(url_path='/home/events/')
+        self.fr_locale = Locale.objects.create(language_code='fr')
+        self.translated_events_page = self.events_page.copy_for_translation(self.fr_locale, copy_parents=True)
+        self.user = self.login()
+
+    def test_locale_selector(self):
+        response = self.client.get(
+            reverse('wagtailadmin_pages:add', args=['tests', 'eventpage', self.events_page.id])
+        )
+
+        self.assertContains(response, '<li class="header-meta--locale">')
+
+        add_translation_url = reverse('wagtailadmin_pages:add', args=['tests', 'eventpage', self.translated_events_page.id])
+        self.assertContains(response, f'<a href="{add_translation_url}" aria-label="French" class="u-link is-live">')
+
+    @override_settings(WAGTAIL_I18N_ENABLED=False)
+    def test_locale_selector_not_present_when_i18n_disabled(self):
+        response = self.client.get(
+            reverse('wagtailadmin_pages:add', args=['tests', 'eventpage', self.events_page.id])
+        )
+
+        self.assertNotContains(response, '<li class="header-meta--locale">')
+
+        add_translation_url = reverse('wagtailadmin_pages:add', args=['tests', 'eventpage', self.translated_events_page.id])
+        self.assertNotContains(response, f'<a href="{add_translation_url}" aria-label="French" class="u-link is-live">')
+
+    def test_locale_dropdown_not_present_without_permission_to_add(self):
+        # Remove user's permissions to add in the French tree
+        group = Group.objects.get(name='Moderators')
+        GroupPagePermission.objects.create(
+            group=group,
+            page=self.events_page,
+            permission_type='add',
+        )
+        self.user.is_superuser = False
+        self.user.user_permissions.add(
+            Permission.objects.get(content_type__app_label='wagtailadmin', codename='access_admin')
+        )
+        self.user.groups.add(group)
+        self.user.save()
+
+        # Locale indicator should exist, but the "French" option should be hidden
+        response = self.client.get(
+            reverse('wagtailadmin_pages:add', args=['tests', 'eventpage', self.events_page.id])
+        )
+
+        self.assertContains(response, '<li class="header-meta--locale">')
+
+        add_translation_url = reverse('wagtailadmin_pages:add', args=['tests', 'eventpage', self.translated_events_page.id])
+        self.assertNotContains(response, f'<a href="{add_translation_url}" aria-label="French" class="u-link is-live">')

wagtail/admin/views/pages/create.py

@@ -1,3 +1,4 @@
+from django.conf import settings
 from django.contrib.contenttypes.models import ContentType
 from django.core.exceptions import PermissionDenied
 from django.http import Http404
@@ -13,7 +14,7 @@ from wagtail.admin import messages, signals
 from wagtail.admin.action_menu import PageActionMenu
 from wagtail.admin.views.generic import HookResponseMixin
 from wagtail.admin.views.pages.utils import get_valid_next_url_from_request
-from wagtail.core.models import Page
+from wagtail.core.models import Page, UserPagePermissionsProxy
 
 
 def add_subpage(request, parent_page_id):
@@ -254,5 +255,25 @@ class CreateView(TemplateResponseMixin, ContextMixin, HookResponseMixin, View):
             'form': self.form,
             'next': self.next_url,
             'has_unsaved_changes': self.has_unsaved_changes,
+            'locale': None,
+            'translations': [],
         })
+
+        if getattr(settings, 'WAGTAIL_I18N_ENABLED', False):
+            user_perms = UserPagePermissionsProxy(self.request.user)
+
+            context.update({
+                'locale': self.parent_page.locale,
+                'translations': [
+                    {
+                        'locale': translation.locale,
+                        'url': reverse('wagtailadmin_pages:add', args=[self.page_content_type.app_label, self.page_content_type.model, translation.id]),
+                    }
+                    for translation in self.parent_page.get_translations().only('id', 'locale').select_related('locale')
+                    if user_perms.for_page(translation).can_add_subpage()
+                    and self.page_class in translation.specific_class.creatable_subpage_models()
+                    and self.page_class.can_create_at(translation)
+                ],
+            })
+
         return context