add ability for page.copy to copy ParentalManyToMany field relations

CHANGELOG.txt

@@ -20,6 +20,7 @@ Changelog
  * Fix: Parent page link in page chooser search results no longer navigates away (Asanka Lihiniyagoda, Sævar Öfjörð Magnússon)
  * Fix: `routablepageurl` tag now correctly omits domain part when multiple sites exist at the same root (Gassan Gousseinov)
  * Fix: Added missing collection column specifier on document listing template (Sergey Fedoseev)
+ * Fix: Page Copy will now also copy ParentalManyToMany field relations (LB (Ben Johnston))
 
 
 2.4 (19.12.2018)

docs/releases/2.5.rst

@@ -35,6 +35,7 @@ Bug fixes
  * Parent page link in page chooser search results no longer navigates away (Asanka Lihiniyagoda, Sævar Öfjörð Magnússon)
  * ``routablepageurl`` tag now correctly omits domain part when multiple sites exist at the same root (Gassan Gousseinov)
  * Added missing collection column specifier on document listing template (Sergey Fedoseev)
+ * Page Copy will now also copy ParentalManyToMany field relations (LB (Ben Johnston))
 
 
 Upgrade considerations

wagtail/core/models.py

@@ -22,7 +22,8 @@ from django.utils import timezone
 from django.utils.functional import cached_property
 from django.utils.text import capfirst, slugify
 from django.utils.translation import ugettext_lazy as _
-from modelcluster.models import ClusterableModel, get_all_child_relations
+from modelcluster.models import (
+    ClusterableModel, get_all_child_m2m_relations, get_all_child_relations)
 from treebeard.mp_tree import MP_Node
 
 from wagtail.core.query import PageQuerySet, TreeQuerySet
@@ -1070,6 +1071,14 @@ class Page(AbstractPage, index.Indexed, ClusterableModel, metaclass=PageBase):
 
             specific_dict[field.name] = getattr(specific_self, field.name)
 
+        # copy child m2m relations
+        for related_field in get_all_child_m2m_relations(specific_self):
+            field = getattr(specific_self, related_field.name)
+            if field and hasattr(field, 'all'):
+                values = field.all()
+                if values:
+                    specific_dict[related_field.name] = values
+
         # New instance from prepared dict values, in case the instance class implements multiple levels inheritance
         page_copy = self.specific_class(**specific_dict)
 

wagtail/core/tests/test_page_model.py

@@ -16,8 +16,8 @@ from wagtail.core.models import Page, PageManager, Site, get_page_models
 from wagtail.tests.testapp.models import (
     AbstractPage, Advert, AlwaysShowInMenusPage, BlogCategory, BlogCategoryBlogPage, BusinessChild,
     BusinessIndex, BusinessNowherePage, BusinessSubIndex, CustomManager, CustomManagerPage,
-    CustomPageQuerySet, EventIndex, EventPage, GenericSnippetPage, ManyToManyBlogPage, MTIBasePage,
-    MTIChildPage, MyCustomPage, OneToOnePage, PageWithExcludedCopyField, SimplePage,
+    CustomPageQuerySet, EventCategory, EventIndex, EventPage, GenericSnippetPage, ManyToManyBlogPage,
+    MTIBasePage, MTIChildPage, MyCustomPage, OneToOnePage, PageWithExcludedCopyField, SimplePage,
     SingleEventPage, SingletonPage, StandardIndex, TaggedPage)
 from wagtail.tests.utils import WagtailTestUtils
 
@@ -702,6 +702,41 @@ class TestCopyPage(TestCase):
             "Child objects defined on the superclass were removed from the original page"
         )
 
+    def test_copy_page_copies_parental_relations(self):
+        """Test that a page will be copied with parental many to many relations intact."""
+        christmas_event = EventPage.objects.get(url_path='/home/events/christmas/')
+        summer_category = EventCategory.objects.create(name='Summer')
+        holiday_category = EventCategory.objects.create(name='Holidays')
+
+        # add parental many to many relations
+        christmas_event.categories = (summer_category, holiday_category)
+        christmas_event.save()
+
+        # Copy it
+        new_christmas_event = christmas_event.copy(
+            update_attrs={'title': "New christmas event", 'slug': 'new-christmas-event'}
+        )
+
+        # check that original eventt is untouched
+        self.assertEqual(
+            christmas_event.categories.count(),
+            2,
+            "Child objects (parental many to many) defined on the superclass were removed from the original page"
+        )
+
+        # check that parental many to many are copied
+        self.assertEqual(
+            new_christmas_event.categories.count(),
+            2,
+            "Child objects (parental many to many) weren't copied"
+        )
+
+        # check that the original and copy are related to the same categories
+        self.assertEqual(
+            new_christmas_event.categories.all().in_bulk(),
+            christmas_event.categories.all().in_bulk()
+        )
+
     def test_copy_page_copies_revisions(self):
         christmas_event = EventPage.objects.get(url_path='/home/events/christmas/')
         christmas_event.save_revision()