Add alias_of field to Page

docs/reference/pages/model_reference.rst

@@ -123,6 +123,12 @@ Database fields
 
         The date/time when the page was locked.
 
+    .. attribute:: alias_of
+
+        (foreign key to another page)
+
+        If set, this page is an alias of the page referenced in this field.
+
 Methods and properties
 ~~~~~~~~~~~~~~~~~~~~~~
 

wagtail/core/migrations/0058_page_alias_of.py

@@ -0,0 +1,19 @@
+# Generated by Django 3.0.9 on 2020-08-04 12:38
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('wagtailcore', '0057_page_locale_fields_notnull'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='page',
+            name='alias_of',
+            field=models.ForeignKey(blank=True, editable=False, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='aliases', to='wagtailcore.Page'),
+        ),
+    ]

wagtail/core/models.py

@@ -760,6 +760,18 @@ class Page(AbstractPage, index.Indexed, ClusterableModel, metaclass=PageBase):
         editable=False
     )
 
+    # If non-null, this page is an alias of the linked page
+    # This means the page is kept in sync with the live version
+    # of the linked pages and is not editable by users.
+    alias_of = models.ForeignKey(
+        'self',
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        editable=False,
+        related_name='aliases',
+    )
+
     search_fields = [
         index.SearchField('title', partial_match=True, boost=2),
         index.AutocompleteField('title'),
@@ -2255,11 +2267,13 @@ class Page(AbstractPage, index.Indexed, ClusterableModel, metaclass=PageBase):
         * ``locked_at``
         * ``latest_revision_created_at``
         * ``first_published_at``
+        * ``alias_of``
         """
 
         obj = self.specific_class.from_json(content_json)
 
         # These should definitely never change between revisions
+        obj.id = self.id
         obj.pk = self.pk
         obj.content_type = self.content_type
 
@@ -2285,6 +2299,7 @@ class Page(AbstractPage, index.Indexed, ClusterableModel, metaclass=PageBase):
         obj.first_published_at = self.first_published_at
         obj.translation_key = self.translation_key
         obj.locale = self.locale
+        obj.alias_of_id = self.alias_of_id
 
         return obj