Extending the navigation menu

You may have noticed that while our Polls application has been integrated into the CMS, with plugins, toolbar menu items and so on, the site’s navigation menu is still only determined by django CMS Pages.

We can hook into the django CMS menu system to add our own nodes to that navigation menu.

Create the toolbar menu

We create the menu using a CMSAttachMenu sub-class, and use the get_nodes() method to add the nodes.

For this we need a file called cms_menus.py in our application. Add cms_menus.py in polls_cms_integration/:

from django.core.urlresolvers import reverse
from django.utils.translation import ugettext_lazy as _
from cms.menu_bases import CMSAttachMenu
from menus.base import NavigationNode
from menus.menu_pool import menu_pool
from polls.models import Poll
class PollsMenu(CMSAttachMenu):
    name = _("Polls Menu")  # give the menu a name this is required.
    def get_nodes(self, request):
        nodes = []
        # loop over all the Poll objects in the database
        for poll in Poll.objects.all():
            # create a NavigationNode based on each one
            node = NavigationNode(
                title=poll.question,
                url=reverse('polls:detail', args=(poll.pk,)),
                id=poll.pk,
            )
            nodes.append(node)
        return nodes
menu_pool.register_menu(PollsMenu)

What’s happening here:

• we define a PollsMenu class, and register it
• we give the class a name attribute (will be displayed in admin)
• in its get_nodes() method, we build and return a list of nodes, where:
• first we get all the Poll objects
• … and then create a NavigationNode object from each one
• … and return a list of these NavigationNodes

Apply the menu to a page

This menu class is not active until attached to a page.

In the Polls page’s Advanced settings, choose “Polls Menu” in the Attached menu field and save.

You’ll now see that every Poll is represented as a node in a sub-menu for the Polls page.

Apply it automatically

Note that you could have added the menu to any page. However, we can also attach a menu like this not just to a page, but to an apphook - so that whatever page an application is attached to, the menu will be attached to.

We’ll do this in the cms_apps.py, where the apphook class PollsApphook lives - the amended lines are highlighted:

 from django.utils.translation import ugettext_lazy as _
 from cms.app_base import CMSApp
 from cms.apphook_pool import apphook_pool
 from polls_cms_integration.cms_menus import PollsMenu
 class PollsApphook(CMSApp):
     name = _("Polls Application")   # give your application a name
     urls = ["polls.urls"]           # link it to URL configuration(s)
     app_name = "polls"              # set the default application namespace
     menus = [PollsMenu]             # set a menu for this apphook

Any page that is attached to the Polls application will now have sub-menu items for each of the Polls in the database. It doesn’t stop you from also adding menus to pages manually, but guarantees that they will appear on the Polls page at least.