Replace PageRevision with generic Revision model

CHANGELOG.txt

@@ -16,6 +16,7 @@ Changelog
  * Fix: Typo in `ResumeWorkflowActionFormatter` message (Stefan Hammer)
  * Fix: Throw a meaningful error when saving an image to an unrecognised image format (Christian Franke)
  * Fix: Remove extra padding for headers with breadcrumbs on mobile viewport (Steven Steinwand)
+ * Replace `PageRevision` with generic `Revision` model (Sage Abdullah)
 
 
 3.0 (16.05.2022)

docs/reference/pages/model_reference.rst

@@ -484,25 +484,43 @@ The ``locale`` and ``translation_key`` fields have a unique key constraint to pr
     .. autoattribute:: localized
 
 
-.. _page-revision-model-ref:
+.. _revision-model-ref:
 
-``PageRevision``
-================
+``Revision``
+============
 
-Every time a page is edited a new ``PageRevision`` is created and saved to the database. It can be used to find the full history of all changes that have been made to a page and it also provides a place for new changes to be kept before going live.
+Every time a page is edited a new ``Revision`` is created and saved to the database. It can be used to find the full history of all changes that have been made to a page and it also provides a place for new changes to be kept before going live.
 
 - Revisions can be created from any :class:`~wagtail.models.Page` object by calling its :meth:`~Page.save_revision` method
-- The content of the page is JSON-serialisable and stored in the :attr:`~PageRevision.content` field
-- You can retrieve a ``PageRevision`` as a :class:`~wagtail.models.Page` object by calling the :meth:`~PageRevision.as_page_object` method
+- The content of the page is JSON-serialisable and stored in the :attr:`~Revision.content` field
+- You can retrieve a ``Revision`` as a :class:`~wagtail.models.Page` object by calling the :meth:`~Revision.as_object` method
+
+.. versionchanged:: 4.0
+
+    The model has been renamed from ``PageRevision`` to ``Revision`` and it now references the ``Page`` model using a combination of an ``object_id`` :class:`~django.db.models.CharField` and foreign keys to :class:`~django.contrib.contenttypes.models.ContentType`.
 
 Database fields
 ~~~~~~~~~~~~~~~
 
-.. class:: PageRevision
+.. class:: Revision
 
-    .. attribute:: page
+    .. attribute:: content_type
 
-        (foreign key to :class:`~wagtail.models.Page`)
+        (foreign key to :class:`~django.contrib.contenttypes.models.ContentType`)
+
+        This is the content type of the object this revision belongs to. For page revisions, this means the content type of the specific page type.
+
+    .. attribute:: base_content_type
+
+        (foreign key to :class:`~django.contrib.contenttypes.models.ContentType`)
+
+        This is the base content type of the object this revision belongs to. For page revisions, this means the content type of the :class:`~wagtail.models.Page` model.
+
+    .. attribute:: object_id
+
+        (string)
+
+        This represents the primary key of the object this revision belongs to.
 
     .. attribute:: submitted_for_moderation
 
@@ -536,38 +554,56 @@ Database fields
 Managers
 ~~~~~~~~
 
-.. class:: PageRevision
+.. class:: Revision
     :noindex:
 
     .. attribute:: objects
 
-        This manager is used to retrieve all of the ``PageRevision`` objects in the database
+        This manager is used to retrieve all of the ``Revision`` objects in the database.
 
         Example:
 
         .. code-block:: python
 
-            PageRevision.objects.all()
+            Revision.objects.all()
+
+    .. attribute:: page_revisions
+
+        This manager is used to retrieve all of the ``Revision`` objects that belong to pages.
+
+        Example:
+
+        .. code-block:: python
+
+            Revision.page_revisions.all()
+
+        .. versionadded:: 4.0
+
+            This manager is added as a shorthand to retrieve page revisions.
 
     .. attribute:: submitted_revisions
 
-        This manager is used to retrieve all of the ``PageRevision`` objects that are awaiting moderator approval
+        This manager is used to retrieve all of the ``Revision`` objects that are awaiting moderator approval.
 
         Example:
 
         .. code-block:: python
 
-            PageRevision.submitted_revisions.all()
+            Revision.submitted_revisions.all()
 
 Methods and properties
 ~~~~~~~~~~~~~~~~~~~~~~
 
-.. class:: PageRevision
+.. class:: Revision
     :noindex:
 
-    .. automethod:: as_page_object
+    .. automethod:: as_object
+
+        This method retrieves this revision as an instance of its object's specific class. If the revision belongs to a page, it will be an instance of the :class:`~wagtail.models.Page`'s specific subclass.
 
-        This method retrieves this revision as an instance of its :class:`~wagtail.models.Page` subclass.
+        .. versionadded:: 4.0
+
+            This method has been renamed from ``as_page_object()`` to ``as_object()``.
 
     .. automethod:: approve_moderation
 
@@ -579,11 +615,19 @@ Methods and properties
 
     .. automethod:: is_latest_revision
 
-        Returns ``True`` if this revision is its page's latest revision
+        Returns ``True`` if this revision is the object's latest revision
 
     .. automethod:: publish
 
-        Calling this will copy the content of this revision into the live page object. If the page is in draft, it will be published.
+        Calling this will copy the content of this revision into the live object. If the object is in draft, it will be published.
+
+    .. autoattribute:: content_object
+
+        This property returns the object this revision belongs to as an instance of the base class.
+
+    .. autoattribute:: specific_content_object
+
+        This property returns the object this revision belongs to as an instance of the specific class.
 
 ``GroupPagePermission``
 =======================
@@ -837,7 +881,7 @@ Database fields
 
     .. attribute:: page_revision
 
-        (foreign key to ``PageRevision``)
+        (foreign key to ``Revision``)
 
         The page revision this task state was created on.
 
@@ -1049,7 +1093,7 @@ Database fields
 
     .. attribute:: revision
 
-        (foreign key to :class:`PageRevision`)
+        (foreign key to :class:`Revision`)
 
         A foreign key to the current page revision.
 
@@ -1111,7 +1155,7 @@ Database fields
 
     .. attribute:: revision_created
 
-        (foreign key to :class:`PageRevision`)
+        (foreign key to :class:`Revision`)
 
         A foreign key to the revision on which the comment was created.
 

docs/reference/signals.rst

@@ -3,7 +3,7 @@
 Signals
 =======
 
-Wagtail's :ref:`page-revision-model-ref` and :ref:`page-model-ref` implement
+Wagtail's :ref:`revision-model-ref` and :ref:`page-model-ref` implement
 :doc:`Signals <topics/signals>` from ``django.dispatch``.
 Signals are useful for creating side-effects from page publish/unpublish events.
 
@@ -13,11 +13,11 @@ For example, you could use signals to send publish notifications to a messaging
 ``page_published``
 ------------------
 
-This signal is emitted from a ``PageRevision`` when a revision is set to `published`.
+This signal is emitted from a ``Revision`` when a page revision is set to `published`.
 
 :sender: The page ``class``.
 :instance: The specific ``Page`` instance.
-:revision: The ``PageRevision`` that was published.
+:revision: The ``Revision`` that was published.
 :kwargs: Any other arguments passed to ``page_published.send()``.
 
 To listen to a signal, implement ``page_published.connect(receiver, sender, **kwargs)``. Here's a simple

docs/releases/4.0.md

@@ -26,6 +26,7 @@ depth: 1
  * Fix typo in `ResumeWorkflowActionFormatter` message (Stefan Hammer)
  * Throw a meaningful error when saving an image to an unrecognised image format (Christian Franke)
  * Remove extra padding for headers with breadcrumbs on mobile viewport (Steven Steinwand)
+ * Replace `PageRevision` with generic `Revision` model (Sage Abdullah)
 
 
 ## Upgrade considerations
@@ -34,8 +35,14 @@ depth: 1
 
 The `wagtail.contrib.modeladmin.helpers.AdminURLHelper` class now accepts a `base_url_path` keyword argument on its constructor. Custom subclasses of this class should be updated to accept this keyword argument.
 
-
 ### Dropped support for Safari 13
 
 Safari 13 will no longer be officially supported as of this release, this deviates the current support for the last 3 version of Safari by a few months and was required to add better support for RTL languages.
 
+### `PageRevision` replaced with `Revision`
+
+The `PageRevision` model has been replaced with a generic `Revision` model. If you use the `PageRevision` model in your code, make sure that:
+
+ * Creation of `PageRevision` objects should be updated to create `Revision` objects using the page's `id` as the `object_id`, the default `Page` model's content type as the `base_content_type`, and the page's specific content type as the `content_type`.
+ * Queries that use the `PageRevision.objects` manager should be updated to use the `Revision.page_revisions` manager.
+ * Queries for `Page` objects that use `PageRevision.page_id` should be updated to cast the `Revision.object_id` to an integer before using it in the query.

wagtail/actions/copy_page.py

@@ -190,7 +190,7 @@ def _copy_page(
                 revision.pk = None
                 revision.submitted_for_moderation = False
                 revision.approved_go_live_at = None
-                revision.page = page_copy
+                revision.object_id = page_copy.id
 
                 # Update ID fields in content
                 revision_content = revision.content

wagtail/actions/publish_page_revision.py

@@ -37,7 +37,7 @@ def __init__(
         self, revision, user=None, changed=True, log_action=True, previous_revision=None
     ):
         self.revision = revision
-        self.page = self.revision.as_page_object()
+        self.page = self.revision.as_object()
         self.user = user
         self.changed = changed
         self.log_action = log_action
@@ -73,7 +73,7 @@ def log_scheduling_action(self):
     def _publish_page_revision(
         self, revision, page, user, changed, log_action, previous_revision
     ):
-        from wagtail.models import COMMENTS_RELATION_NAME, PageRevision
+        from wagtail.models import COMMENTS_RELATION_NAME, Revision
 
         if page.go_live_at and page.go_live_at > timezone.now():
             page.has_unpublished_changes = True
@@ -110,7 +110,7 @@ def _publish_page_revision(
                 page.first_published_at = now
 
             if previous_revision:
-                previous_revision_page = previous_revision.as_page_object()
+                previous_revision_page = previous_revision.as_object()
                 old_page_title = (
                     previous_revision_page.title
                     if page.title != previous_revision_page.title
@@ -119,11 +119,11 @@ def _publish_page_revision(
             else:
                 try:
                     previous = revision.get_previous()
-                except PageRevision.DoesNotExist:
+                except Revision.DoesNotExist:
                     previous = None
                 old_page_title = (
-                    previous.page.title
-                    if previous and page.title != previous.page.title
+                    previous.content_object.title
+                    if previous and page.title != previous.content_object.title
                     else None
                 )
         else:

wagtail/actions/revert_to_page_revision.py

@@ -57,7 +57,7 @@ def check(self, skip_permission_checks=False):
     def execute(self, skip_permission_checks=False):
         self.check(skip_permission_checks=skip_permission_checks)
 
-        return self.revision.as_page_object().save_revision(
+        return self.revision.as_object().save_revision(
             previous_revision=self.revision,
             user=self.user,
             log_action=self.log_action,

wagtail/admin/api/actions/revert_to_page_revision.py

@@ -38,5 +38,5 @@ def execute(self, instance, data):
         except RevertToPageRevisionError as e:
             raise BadRequestError(e.args[0])
 
-        serializer = self.view.get_serializer(new_revision.as_page_object())
+        serializer = self.view.get_serializer(new_revision.as_object())
         return Response(serializer.data, status=status.HTTP_200_OK)

wagtail/admin/mail.py

@@ -73,7 +73,7 @@ def send_moderation_notification(revision, notification, excluded_user=None):
             settings, "WAGTAILADMIN_NOTIFICATION_INCLUDE_SUPERUSERS", True
         )
         recipient_users = users_with_page_permission(
-            revision.page, "publish", include_superusers
+            revision.content_object, "publish", include_superusers
         )
     elif notification in ["rejected", "approved"]:
         # Get submitter

wagtail/admin/templates/wagtailadmin/home/pages_for_moderation.html

@@ -18,25 +18,25 @@ <h2 class="title-wrapper">{% trans 'Pages awaiting moderation' %}</h2>
                 </thead>
                 <tbody>
                     {% for revision in page_revisions_for_moderation %}
-                        {% page_permissions revision.page as page_perms %}
+                        {% page_permissions revision.content_object as page_perms %}
                         <tr>
                             <td class="title" valign="top">
                                 <div class="title-wrapper">
                                     {% if page_perms.can_edit %}
-                                        <a href="{% url 'wagtailadmin_pages:edit' revision.page.id %}" title="{% trans 'Edit this page' %}">{{ revision.page.specific_deferred.get_admin_display_title }}</a>
-                                    {% elif revision.page.is_previewable %}
-                                        <a href="{% url 'wagtailadmin_pages:preview_for_moderation' revision.id %}" title="{% trans 'Preview this page' %}">{{ revision.page.specific_deferred.get_admin_display_title }}</a>
+                                        <a href="{% url 'wagtailadmin_pages:edit' revision.object_id %}" title="{% trans 'Edit this page' %}">{{ revision.content_object.specific_deferred.get_admin_display_title }}</a>
+                                    {% elif revision.content_object.is_previewable %}
+                                        <a href="{% url 'wagtailadmin_pages:preview_for_moderation' revision.id %}" title="{% trans 'Preview this page' %}">{{ revision.content_object.specific_deferred.get_admin_display_title }}</a>
                                     {% else %}
-                                        {{ revision.page.specific_deferred.get_admin_display_title }}
+                                        {{ revision.content_object.specific_deferred.get_admin_display_title }}
                                     {% endif %}
 
                                     {% i18n_enabled as show_locale_labels %}
-                                    {% if show_locale_labels and revision.page.locale_id %}
-                                        {% locale_label_from_id revision.page.locale_id as locale_label %}
+                                    {% if show_locale_labels and revision.content_object.locale_id %}
+                                        {% locale_label_from_id revision.content_object.locale_id as locale_label %}
                                         <span class="status-tag status-tag--label">{{ locale_label }}</span>
                                     {% endif %}
-                                    {% include "wagtailadmin/pages/listing/_privacy_indicator.html" with page=revision.page %}
-                                    {% include "wagtailadmin/pages/listing/_locked_indicator.html" with page=revision.page %}
+                                    {% include "wagtailadmin/pages/listing/_privacy_indicator.html" with page=revision.content_object %}
+                                    {% include "wagtailadmin/pages/listing/_locked_indicator.html" with page=revision.content_object %}
                                 </div>
                                 <ul class="actions">
                                     <li>
@@ -52,18 +52,18 @@ <h2 class="title-wrapper">{% trans 'Pages awaiting moderation' %}</h2>
                                         </form>
                                     </li>
                                     {% if page_perms.can_edit %}
-                                        <li><a href="{% url 'wagtailadmin_pages:edit' revision.page.id %}" class="button button-small button-secondary">{% trans 'Edit' %}</a></li>
+                                        <li><a href="{% url 'wagtailadmin_pages:edit' revision.object_id %}" class="button button-small button-secondary">{% trans 'Edit' %}</a></li>
                                     {% endif %}
-                                    {% if revision.page.is_previewable %}
+                                    {% if revision.content_object.is_previewable %}
                                         <li><a href="{% url 'wagtailadmin_pages:preview_for_moderation' revision.id %}" class="button button-small button-secondary" target="_blank" rel="noreferrer">{% trans 'Preview' %}</a></li>
                                     {% endif %}
                                 </ul>
                             </td>
                             <td valign="top">
-                                <a href="{% url 'wagtailadmin_explore' revision.page.get_parent.id %}">{{ revision.page.get_parent.specific_deferred.get_admin_display_title }}</a>
+                                <a href="{% url 'wagtailadmin_explore' revision.content_object.get_parent.id %}">{{ revision.content_object.get_parent.specific_deferred.get_admin_display_title }}</a>
                             </td>
                             <td class="type" valign="top">
-                                {{ revision.page.content_type.model_class.get_verbose_name }}
+                                {{ revision.content_object.content_type.model_class.get_verbose_name }}
                             </td>
                             <td valign="top">
                                 <div class="human-readable-date" title="{{ revision.created_at|date:"DATETIME_FORMAT" }}">{% blocktrans trimmed with time_period=revision.created_at|timesince_simple %}{{ time_period }}{% endblocktrans %} </div>