Question

I have a custom app inside django-cms and have the need to attach a submenu to my app.
I’ve followed the guides and examples I’ve found to do this (see the Portfolio example given by Brandon here: custom views within Djangocms?), and managed to get the submenu up and running.

By expanding on the example provided above; What if this Portfolio app presented here, consisted of a small number of different views (create view, detail view and perhaps a couple of other related views). What if I needed to build a submenu to hold the choices related to user navigation in this small app. And what if the navigation should present choices based on selected content in the views (“Edit” only if a portfolio is selected or similar).
The submenu would have to know what Portfolio was selected, right? Or at least that a Portfolio is in fact selected and in view.

How can I transfer to my implementation of CMSAttachMenu what my view allready knows? In my case, I’m implementing an app dealing with meetups or “Events”. The example below does not work, because the Event object is obviously not registered in the request, but it illustrates what I want:

# menu.py
from django.core.urlresolvers import reverse
from menus.base import NavigationNode
from menus.menu_pool import menu_pool
from cms.menu_bases import CMSAttachMenu
from App.apps.event.models import Event
from django.utils.translation import ugettext_lazy as _
import logging

logger = logging.getLogger('instant.event')


class EventMenu(CMSAttachMenu):

    name = _("Event Sub-Menu")

    def get_nodes(self, request):
        nodes = []
        nodes.append(NavigationNode(_('Create new events'), reverse("admin:event_event_add"), 1 + len(nodes), 0))

        if hasattr(request, 'event'):
            if request.event.is_registered_to_event(request.user):
                nodes.append(NavigationNode(_('Unregister from this event'), reverse("unregister_from_event"), 1 + len(nodes), 0))
            else:
                nodes.append(NavigationNode(_('Register to participate in this event'), reverse("unregister_from_event"), 1 + len(nodes), 0))

        if request.user.is_superuser():
            nodes.append(NavigationNode(_('Register other participant to this event'), reverse("register_admin", args=(request.event.id)), 1 + len(nodes), 0))

        nodes.append(NavigationNode(_('Back to list of events'), reverse("events"), 1 + len(nodes), 0))
    return nodes

menu_pool.register_menu(EventMenu)

Answer 1

This was a hard one, but the following would solve it (showing only relevant parts):

cms_app.py

from cms.app_base import CMSApp
from cms.apphook_pool import apphook_pool
from django.utils.translation import ugettext_lazy as _

class EventsApphook(CMSApp):
    name = _("Event")
    urls = ["App.apps.event.urls"]
apphook_pool.register(EventsApphook)

menu.py

from cms.menu_bases import CMSAttachMenu
from menus.base import NavigationNode
from menus.menu_pool import menu_pool
from django.utils.translation import ugettext_lazy as _

menuNodes = []

class EventMenu(CMSAttachMenu):
    name = _("Event Sub-Menu")
    def get_nodes(self, request):
        return menuNodes
menu_pool.register_menu(EventMenu)

def add_menu_node(text, url):
    # only add a given url once
    if len(list(n for n in menuNodes if n.url == url)) == 0:
        menuNodes.append(NavigationNode(text, url, 1 + len(menuNodes), 0))
        menu_pool.clear()

views.py

from django.views.generic.detail import DetailView
from django.core.urlresolvers import reverse
from django.utils.translation import ugettext_lazy as _
from App.apps.event.menu import add_menu_node
from App.apps.event.models import Event

class EventMenuMixin(object):
    def get_context_data(self, **kwargs):
        context = super(EventMenuMixin, self).get_context_data(**kwargs)
        member = self.request.user

        if 'pk' in self.kwargs.keys():
            event = Event.objects.get(id=self.kwargs['pk'])
            if event.is_registered_to_event(member):
                add_menu_node(_('Unregister from this event'), reverse("unregister_from_event"))
            else:
                add_menu_node(_('Register to participate in this event'), reverse("register_to_event", args=(self.kwargs['pk'])))

        add_menu_node(_("Create new events"), reverse("admin:event_event_add"))
        return context

class EventDetailView(EventMenuMixin, DetailView):
    model = Event
    template_name = 'event/event_detail.html'
    context_object_name = 'event'

I hope this will help others in the same predicament as me.