Allow deleting the default locale (#6553)

Fixes #6533

CHANGELOG.txt

@@ -15,6 +15,7 @@ Changelog
  * Fix: Handle `get_supported_language_variant` returning a language variant not in `LANGUAGES` (Matt Westcott)
  * Fix: Reinstate missing icon on settings edit view (Jérôme Lebleu)
  * Fix: Avoid performance and pagination logic issues with a large number of languages (Karl Hobley)
+ * Fix: Allow deleting the default locale (Matt Westcott)
 
 
 2.11.1 (06.11.2020)

docs/releases/2.11.2.rst

@@ -18,3 +18,4 @@ Bug fixes
  * Handle ``get_supported_language_variant`` returning a language variant not in ``LANGUAGES`` (Matt Westcott)
  * Reinstate missing icon on settings edit view (Jérôme Lebleu)
  * Avoid performance and pagination logic issues with a large number of languages (Karl Hobley)
+ * Allow deleting the default locale (Matt Westcott)

wagtail/core/models.py

@@ -373,6 +373,26 @@ class Locale(models.Model):
         except (cls.DoesNotExist, LookupError):
             return cls.get_default()
 
+    @transaction.atomic
+    def delete(self, *args, **kwargs):
+        # if we're deleting the locale used on the root page node, reassign that to a new locale first
+        root_page_with_this_locale = Page.objects.filter(depth=1, locale=self)
+        if root_page_with_this_locale.exists():
+            # Select the default locale, if one exists and isn't the one being deleted
+            try:
+                new_locale = Locale.get_default()
+                default_locale_is_ok = (new_locale != self)
+            except (Locale.DoesNotExist, LookupError):
+                default_locale_is_ok = False
+
+            if not default_locale_is_ok:
+                # fall back on any remaining locale
+                new_locale = Locale.all_objects.exclude(pk=self.pk).first()
+
+            root_page_with_this_locale.update(locale=new_locale)
+
+        return super().delete(*args, **kwargs)
+
     def language_code_is_valid(self):
         return self.language_code in get_content_languages()
 

wagtail/locales/tests.py

@@ -1,8 +1,8 @@
 from django.contrib.messages import get_messages
-from django.test import TestCase
+from django.test import TestCase, override_settings
 from django.urls import reverse
 
-from wagtail.core.models import Locale
+from wagtail.core.models import Locale, Page
 from wagtail.tests.utils import WagtailTestUtils
 
 
@@ -175,6 +175,10 @@ class TestLocaleDeleteView(TestCase, WagtailTestUtils):
         self.assertFalse(Locale.objects.filter(language_code='fr').exists())
 
     def test_cannot_delete_locales_with_pages(self):
+        # create a French locale so that the deletion is not rejected on grounds of being the only
+        # existing locale
+        Locale.objects.create(language_code='fr')
+
         response = self.post()
 
         self.assertEqual(response.status_code, 200)
@@ -186,3 +190,76 @@ class TestLocaleDeleteView(TestCase, WagtailTestUtils):
 
         # Check that the locale was not deleted
         self.assertTrue(Locale.objects.filter(language_code='en').exists())
+
+    @override_settings(
+        LANGUAGE_CODE='de-at',
+        WAGTAIL_CONTENT_LANGUAGES=[
+            ('en', 'English'),
+            ('fr', 'French'),
+            ('de', 'German'),
+            ('pl', 'Polish'),
+            ('ja', 'Japanese')
+        ]
+    )
+    def test_can_delete_default_locale(self):
+        # The presence of the locale on the root page node (if that's the only thing using the
+        # locale) should not prevent deleting it
+
+        for lang in ('fr', 'de', 'pl', 'ja'):
+            Locale.objects.create(language_code=lang)
+
+        self.assertTrue(Page.get_first_root_node().locale.language_code, 'en')
+        Page.objects.filter(depth__gt=1).delete()
+        response = self.post()
+
+        # Should redirect back to index
+        self.assertRedirects(response, reverse('wagtaillocales:index'))
+
+        # Check that the locale was deleted
+        self.assertFalse(Locale.objects.filter(language_code='en').exists())
+
+        # root node's locale should now have been reassigned to the one matching the current
+        # LANGUAGE_CODE
+        self.assertTrue(Page.get_first_root_node().locale.language_code, 'de')
+
+    @override_settings(
+        LANGUAGE_CODE='de-at',
+        WAGTAIL_CONTENT_LANGUAGES=[
+            ('en', 'English'),
+            ('fr', 'French'),
+            ('de', 'German'),
+            ('pl', 'Polish'),
+            ('ja', 'Japanese')
+        ]
+    )
+    def test_can_delete_default_locale_when_language_code_has_no_locale(self):
+        Locale.objects.create(language_code='fr')
+
+        self.assertTrue(Page.get_first_root_node().locale.language_code, 'en')
+        Page.objects.filter(depth__gt=1).delete()
+        response = self.post()
+
+        # Should redirect back to index
+        self.assertRedirects(response, reverse('wagtaillocales:index'))
+
+        # Check that the locale was deleted
+        self.assertFalse(Locale.objects.filter(language_code='en').exists())
+
+        # root node's locale should now have been reassigned to 'fr' despite that not matching
+        # LANGUAGE_CODE (because it's the only remaining Locale record)
+        self.assertTrue(Page.get_first_root_node().locale.language_code, 'fr')
+
+    def test_cannot_delete_last_remaining_locale(self):
+        Page.objects.filter(depth__gt=1).delete()
+
+        response = self.post()
+
+        self.assertEqual(response.status_code, 200)
+
+        # Check error message
+        messages = list(get_messages(response.wsgi_request))
+        self.assertEqual(messages[0].level_tag, 'error')
+        self.assertEqual(messages[0].message, "This locale cannot be deleted because there are no other locales.\n\n\n\n\n")
+
+        # Check that the locale was not deleted
+        self.assertTrue(Locale.objects.filter(language_code='en').exists())

wagtail/locales/views.py

@@ -43,14 +43,25 @@ class EditView(generic.EditView):
 
 class DeleteView(generic.DeleteView):
     success_message = gettext_lazy("Locale '{0}' deleted.")
-    cannot_delete_message = gettext_lazy("This locale cannot be deleted because there are pages and/or other objects using it.")
     page_title = gettext_lazy("Delete locale")
     confirmation_message = gettext_lazy("Are you sure you want to delete this locale?")
     template_name = 'wagtaillocales/confirm_delete.html'
     queryset = Locale.all_objects.all()
 
     def can_delete(self, locale):
-        return get_locale_usage(locale) == (0, 0)
+        if not self.queryset.exclude(pk=locale.pk).exists():
+            self.cannot_delete_message = gettext_lazy(
+                "This locale cannot be deleted because there are no other locales."
+            )
+            return False
+
+        if get_locale_usage(locale) != (0, 0):
+            self.cannot_delete_message = gettext_lazy(
+                "This locale cannot be deleted because there are pages and/or other objects using it."
+            )
+            return False
+
+        return True
 
     def get_context_data(self, object=None):
         context = context = super().get_context_data()