Fix copy_for_translation on inherited and clusterable models

wagtail/core/models.py

@@ -150,7 +150,11 @@ def _copy(source, exclude_fields=None, update_attrs=None):
                 continue
             setattr(target, field, value)
 
-    child_object_map = source.copy_all_child_relations(target, exclude=exclude_fields)
+    if isinstance(source, ClusterableModel):
+        child_object_map = source.copy_all_child_relations(target, exclude=exclude_fields)
+    else:
+        child_object_map = {}
+
     return target, child_object_map
 
 
@@ -489,10 +493,15 @@ def copy_for_translation(self, locale):
 
         Note that the copy is initially unsaved.
         """
-        translated = self.__class__.objects.get(id=self.id)
-        translated.id = None
+        translated, child_object_map = _copy(self)
         translated.locale = locale
 
+        # Update locale on any translatable child objects as well
+        # Note: If this is not a subclass of ClusterableModel, child_object_map will always be '{}'
+        for (child_relation, old_pk), child_object in child_object_map.items():
+            if isinstance(child_object, TranslatableMixin):
+                child_object.locale = locale
+
         return translated
 
     def get_default_locale(self):

wagtail/core/tests/test_translatablemixin.py

@@ -5,7 +5,9 @@
 from django.test import TestCase
 
 from wagtail.core.models import Locale
-from wagtail.tests.i18n.models import InheritedTestModel, TestModel
+from wagtail.tests.i18n.models import (
+    ClusterableTestModel, ClusterableTestModelChild, ClusterableTestModelTranslatableChild,
+    InheritedTestModel, TestModel)
 
 
 def make_test_instance(model=None, **kwargs):
@@ -108,6 +110,46 @@ def test_get_translation_model(self):
         inherited_model = make_test_instance(model=InheritedTestModel)
         self.assertEqual(inherited_model.get_translation_model(), TestModel)
 
+    def test_copy_inherited_model_for_translation(self):
+        instance = make_test_instance(model=InheritedTestModel)
+        copy = instance.copy_for_translation(locale=self.another_locale)
+
+        self.assertNotEqual(copy, instance)
+        self.assertEqual(copy.translation_key, instance.translation_key)
+        self.assertEqual(copy.locale, self.another_locale)
+
+    def test_copy_clusterable_model_for_translation(self):
+        instance = ClusterableTestModel.objects.create(
+            title="A test clusterable model",
+            children=[
+                ClusterableTestModelChild(field="A non-translatable child object"),
+            ],
+            translatable_children=[
+                ClusterableTestModelTranslatableChild(field="A translatable child object"),
+            ]
+        )
+
+        copy = instance.copy_for_translation(locale=self.another_locale)
+
+        instance_child = instance.children.get()
+        copy_child = copy.children.get()
+        instance_translatable_child = instance.translatable_children.get()
+        copy_translatable_child = copy.translatable_children.get()
+
+        self.assertNotEqual(copy, instance)
+        self.assertEqual(copy.translation_key, instance.translation_key)
+        self.assertEqual(copy.locale, self.another_locale)
+
+        # Check children were copied
+        self.assertNotEqual(copy_child, instance_child)
+        self.assertEqual(copy_child.field, "A non-translatable child object")
+        self.assertNotEqual(copy_translatable_child, instance_translatable_child)
+        self.assertEqual(copy_translatable_child.field, "A translatable child object")
+
+        # Check the translatable childs locale was updated but translation key is the same
+        self.assertEqual(copy_translatable_child.translation_key, instance_translatable_child.translation_key)
+        self.assertEqual(copy_translatable_child.locale, self.another_locale)
+
 
 class TestLocalized(TestCase):
     def setUp(self):

wagtail/tests/i18n/migrations/0002_clusterabletestmodel_clusterabletestmodelchild_clusterabletestmodeltranslatablechild.py

@@ -0,0 +1,59 @@
+# Generated by Django 3.1.6 on 2021-02-16 18:04
+
+from django.db import migrations, models
+import django.db.models.deletion
+import modelcluster.fields
+import uuid
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('wagtailcore', '0061_change_promote_tab_helpt_text_and_verbose_names'),
+        ('i18n', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ClusterableTestModel',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('translation_key', models.UUIDField(default=uuid.uuid4, editable=False)),
+                ('title', models.CharField(max_length=255)),
+                ('locale', models.ForeignKey(editable=False, on_delete=django.db.models.deletion.PROTECT, related_name='+', to='wagtailcore.locale')),
+            ],
+            options={
+                'abstract': False,
+                'unique_together': {('translation_key', 'locale')},
+            },
+        ),
+        migrations.CreateModel(
+            name='ClusterableTestModelChild',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('sort_order', models.IntegerField(blank=True, editable=False, null=True)),
+                ('field', models.TextField()),
+                ('parent', modelcluster.fields.ParentalKey(on_delete=django.db.models.deletion.CASCADE, related_name='children', to='i18n.clusterabletestmodel')),
+            ],
+            options={
+                'ordering': ['sort_order'],
+                'abstract': False,
+            },
+        ),
+        migrations.CreateModel(
+            name='ClusterableTestModelTranslatableChild',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('translation_key', models.UUIDField(default=uuid.uuid4, editable=False)),
+                ('sort_order', models.IntegerField(blank=True, editable=False, null=True)),
+                ('field', models.TextField()),
+                ('locale', models.ForeignKey(editable=False, on_delete=django.db.models.deletion.PROTECT, related_name='+', to='wagtailcore.locale')),
+                ('parent', modelcluster.fields.ParentalKey(on_delete=django.db.models.deletion.CASCADE, related_name='translatable_children', to='i18n.clusterabletestmodel')),
+            ],
+            options={
+                'ordering': ['sort_order'],
+                'abstract': False,
+                'unique_together': {('translation_key', 'locale')},
+            },
+        ),
+    ]

wagtail/tests/i18n/models.py

@@ -1,5 +1,6 @@
 from django.db import models
 from modelcluster.fields import ParentalKey
+from modelcluster.models import ClusterableModel
 
 from wagtail.core.models import Orderable, Page, TranslatableMixin
 
@@ -30,3 +31,20 @@ class TestNonParentalChildObject(TranslatableMixin, Orderable):
         TestPage, on_delete=models.CASCADE, related_name="test_nonparentalchildobjects"
     )
     field = models.TextField()
+
+
+class ClusterableTestModel(TranslatableMixin, ClusterableModel):
+    title = models.CharField(max_length=255)
+
+
+class ClusterableTestModelChild(Orderable):
+    parent = ParentalKey(ClusterableTestModel, on_delete=models.CASCADE, related_name='children')
+    field = models.TextField()
+
+
+class ClusterableTestModelTranslatableChild(TranslatableMixin, Orderable):
+    parent = ParentalKey(ClusterableTestModel, on_delete=models.CASCADE, related_name='translatable_children')
+    field = models.TextField()
+
+    class Meta(TranslatableMixin.Meta, Orderable.Meta):
+        pass