Customising navigation menus

In this document we discuss three different way of customising the navigation menus of django CMS sites.

1. Menus: Statically extend the menu entries
2. Attach Menus: Attach your menu to a page.
3. Navigation Modifiers: Modify the whole menu tree

Menus

Create a menu.py in your application and write the following inside:

from menus.base import Menu, NavigationNode
from menus.menu_pool import menu_pool
from django.utils.translation import ugettext_lazy as _
class TestMenu(Menu):
    def get_nodes(self, request):
        nodes = []
        n = NavigationNode(_('sample root page'), "/", 1)
        n2 = NavigationNode(_('sample settings page'), "/bye/", 2)
        n3 = NavigationNode(_('sample account page'), "/hello/", 3)
        n4 = NavigationNode(_('sample my profile page'), "/hello/world/", 4, 3)
        nodes.append(n)
        nodes.append(n2)
        nodes.append(n3)
        nodes.append(n4)
        return nodes
menu_pool.register_menu(TestMenu)

If you refresh a page you should now see the menu entries from above. The get_nodes function should return a list of NavigationNode instances. A NavigationNode takes the following arguments:

title

What the menu entry should read as

url

Link if menu entry is clicked.

id

A unique id for this menu.

parent_id=None

If this is a child of another node supply the id of the parent here.

parent_namespace=None

If the parent node is not from this menu you can give it the parent namespace. The namespace is the name of the class. In the above example that would be: “TestMenu”

attr=None

A dictionary of additional attributes you may want to use in a modifier or in the template.

visible=True

Whether or not this menu item should be visible.

Additionally, each NavigationNode provides a number of methods which are detailed in the NavigationNode API references.

Customize menus at runtime

To adapt your menus according to request dependent conditions (say: anonymous / logged in user), you can use Navigation Modifiers or you can leverage existing ones.

For example it’s possible to add {'visible_for_anonymous': False} / {'visible_for_authenticated': False} attributes recognized by the django CMS core AuthVisibility modifier.

Complete example:

class UserMenu(Menu):
    def get_nodes(self, request):
            return [
                NavigationNode(_("Profile"), reverse(profile), 1, attr={'visible_for_anonymous': False}),
                NavigationNode(_("Log in"), reverse(login), 3, attr={'visible_for_authenticated': False}),
                NavigationNode(_("Sign up"), reverse(logout), 4, attr={'visible_for_authenticated': False}),
                NavigationNode(_("Log out"), reverse(logout), 2, attr={'visible_for_anonymous': False}),
            ]

Attach Menus

Classes that extend from menus.base.Menu always get attached to the root. But if you want the menu to be attached to a CMS Page you can do that as well.

Instead of extending from Menu you need to extend from cms.menu_bases.CMSAttachMenu and you need to define a name. We will do that with the example from above:

from menus.base import NavigationNode
from menus.menu_pool import menu_pool
from django.utils.translation import ugettext_lazy as _
from cms.menu_bases import CMSAttachMenu
class TestMenu(CMSAttachMenu):
    name = _("test menu")
    def get_nodes(self, request):
        nodes = []
        n = NavigationNode(_('sample root page'), "/", 1)
        n2 = NavigationNode(_('sample settings page'), "/bye/", 2)
        n3 = NavigationNode(_('sample account page'), "/hello/", 3)
        n4 = NavigationNode(_('sample my profile page'), "/hello/world/", 4, 3)
        nodes.append(n)
        nodes.append(n2)
        nodes.append(n3)
        nodes.append(n4)
        return nodes
menu_pool.register_menu(TestMenu)

Now you can link this Menu to a page in the ‘Advanced’ tab of the page settings under attached menu.

Navigation Modifiers

Navigation Modifiers give your application access to navigation menus.

A modifier can change the properties of existing nodes or rearrange entire menus.

An example use-case

A simple example: you have a news application that publishes pages independently of django CMS. However, you would like to integrate the application into the menu structure of your site, so that at appropriate places a News node appears in the navigation menu.

In such a case, a Navigation Modifier is the solution.

How it works

Normally, you’d want to place modifiers in your application’s menu.py.

To make your modifier available, it then needs to be registered with menus.menu_pool.menu_pool.

Now, when a page is loaded and the menu generated, your modifier will be able to inspect and modify its nodes.

A simple modifier looks something like this:

from menus.base import Modifier
from menus.menu_pool import menu_pool
class MyMode(Modifier):
    """
    """
    def modify(self, request, nodes, namespace, root_id, post_cut, breadcrumb):
        if post_cut:
            return nodes
        count = 0
        for node in nodes:
            node.counter = count
            count += 1
        return nodes
menu_pool.register_modifier(MyMode)

It has a method modify() that should return a list of NavigationNode instances. modify() should take the following arguments:

request

A Django request instance. You want to modify based on sessions, or user or permissions?

nodes

All the nodes. Normally you want to return them again.

namespace

A Menu Namespace. Only given if somebody requested a menu with only nodes from this namespace.

root_id

Was a menu request based on an ID?

post_cut

Every modifier is called two times. First on the whole tree. After that the tree gets cut to only show the nodes that are shown in the current menu. After the cut the modifiers are called again with the final tree. If this is the case post_cut is True.

breadcrumb

Is this not a menu call but a breadcrumb call?

Here is an example of a built-in modifier that marks all node levels:

class Level(Modifier):
    """
    marks all node levels
    """
    post_cut = True
    def modify(self, request, nodes, namespace, root_id, post_cut, breadcrumb):
        if breadcrumb:
            return nodes
        for node in nodes:
            if not node.parent:
                if post_cut:
                    node.menu_level = 0
                else:
                    node.level = 0
                self.mark_levels(node, post_cut)
        return nodes
    def mark_levels(self, node, post_cut):
        for child in node.children:
            if post_cut:
                child.menu_level = node.menu_level + 1
            else:
                child.level = node.level + 1
            self.mark_levels(child, post_cut)
menu_pool.register_modifier(Level)