2. Extending the page & title models

New in version 3.0.

You can extend the page and title models with your own fields (e.g. adding an icon for every page) by using the extension models: cms.extensions.PageExtension and cms.extensions.TitleExtension, respectively.

2.1. How To

To add a field to the page model, subclass a class that inherits from cms.extensions.PageExtension. Make sure to import the PageExtension model from the given path. It isn’t importable from cms.models. Your class should live in one of your apps’ models.py. You are free to add any field you want but make sure you don’t use a unique constraint on any of your added fields because uniqueness prevents the copy mechanism of the extension from working correctly. This means that you can’t use one-to-one relations on the extension model. Finally, you’ll need to register the model with the extension_pool.

Here’s a complete example:

from django.db import models

from cms.extensions import PageExtension
from cms.extensions.extension_pool import extension_pool


class IconExtension(PageExtension):
    image = models.ImageField(upload_to='icons')

extension_pool.register(IconExtension)

2.2. Hooking the extension to the admin site

To make your extension editable, create an admin that subclasses cms.extensions.PageExtensionAdmin. This admin handles page permissions. If you want to use your own admin class, make sure to exclude the live versions of the extensions by using filter(extended_page__publisher_is_draft=True) on the queryset.

If you save an extension, the corresponding page is marked as having unpublished changes. To see your extension live make sure to publish the page.

You’ll also want to make your model editable from the cms toolbar in order to associate each instance of the extension model with a page. (Page isn’t an editable attribute in the default admin interface.) The following example, which should live in a file named cms_toolbar.py in one of your apps, adds a menu entry for the extension on each page:

from cms.api import get_page_draft
from cms.toolbar_pool import toolbar_pool
from cms.toolbar_base import CMSToolbar
from cms.utils import get_cms_setting
from cms.utils.permissions import has_page_change_permission
from django.core.urlresolvers import reverse, NoReverseMatch
from django.utils.translation import ugettext_lazy as _
from .models import IconExtension


@toolbar_pool.register
class IconExtensionToolbar(CMSToolbar):
    def populate(self):
        # always use draft if we have a page
        self.page = get_page_draft(self.request.current_page)

        if not self.page:
            # Nothing to do
            return

        # check global permissions if CMS_PERMISSIONS is active
        if get_cms_setting('PERMISSION'):
            has_global_current_page_change_permission = has_page_change_permission(self.request)
        else:
            has_global_current_page_change_permission = False
            # check if user has page edit permission
        can_change = self.request.current_page and self.request.current_page.has_change_permission(self.request)
        if has_global_current_page_change_permission or can_change:
            try:
                icon_extension = IconExtension.objects.get(extended_object_id=self.page.id)
            except IconExtension.DoesNotExist:
                icon_extension = None
            try:
                if icon_extension:
                    url = reverse('admin:myapp_iconextension_change', args=(icon_extension.pk,))
                else:
                    url = reverse('admin:myapp_iconextension_add') + '?extended_object=%s' % self.page.pk
            except NoReverseMatch:
                # not in urls
                pass
            else:
                not_edit_mode = not self.toolbar.edit_mode
                current_page_menu = self.toolbar.get_or_create_menu('page')
                current_page_menu.add_modal_item(_('Page Icon'), url=url, disabled=not_edit_mode)

2.3. Using extensions with menus

If you want the extension to show up in the menu (e.g. if you had created an extension that added an icon to the page) use menu modifiers. Every node.id corresponds to their related page.id. Page.objects.get(pk=node.id) is the way to get the page object. Every page extension has a one-to-one relationship with the page so you can access it by using the reverse relation, e.g. extension = page.yourextensionlowercased. Now you can hook this extension by storing it on the node: node.extension = extension. In the menu template you can access your icon on the child object: child.extension.icon.

Table Of Contents

Previous topic

1. Extending the CMS: Examples

Next topic

3. Custom Plugins

This Page