This is a follow up to the previous post on managing and visualizing trees using django. I've been using MPTT quite a bit now and it's great - also, I looked deeper into the admin integration (basically, the issue of being able of manage trees from within the admin).

The major issue I had with the patch discussed in my previous post was the fact that it is mainly a javascript hack - everything is done in the browser - i.e. it looked wonderful but it didn't really scale up. So if you had a lot of items in your tree (say thousands) the js-driven pagination (basically, hiding and showing things on demand) would crash - at least, it did that to me all the time!

The solution has been to reuse the admin management section from the FeinCMS project - this is a great CMS created by a bunch of django-ers in Switzerland - it relies heavvily on django's admin so they had the same problem when having to provide a way for users to add structure to the pages in a website. With some help from google and Matthias (tx! he's one of the guys behind FeinCMS) I got it all working.. here's the main steps:

1. upgrade to django 1.1 This might not be necessary, cause everything is supposed to work also with the previous release - I tried it with django 1.0 too but I had to fix a couple of urls to make it work (Basically media files which were not loaded properly). So, if you want a hassle-free installation just upgrade to django 1.1 ! (which is great btw)

2. download and add feincms, mptt to you installed apps in settings.py As simple as that.

INSTALLED_APPS = ( .... 'mptt', 'feincms', )

3. specify a url-path for feincms media in settings.py, and also a location (this may vary in your live server, if you want apache to serve these files directly).

FEINCMS_ADMIN_MEDIA = '/feincms_media/' FEINCMS_ADMIN_MEDIA_LOCATION = '/My/local/path/to/feincms/media/'

4. add a url handler for feincms media files in urls.py. Again, these settings are ok on a development server, on production phase you might wanna do things differently :-)

from django.conf import settings urlpatterns = patterns('', ..... (r'^feincms_media/(?P.*)$', 'django.views.static.serve', {'document_root': settings.FEINCMS_ADMIN_MEDIA_LOCATION, 'show_indexes': True}), )

5. register your hierarchical model with mptt, then remember to set the Meta option correctly.. this is needed for a correct display of the tree in the admin (obviously you need to run syncdb to create the table in the db!):

from django.db import models import mptt

class TreeNode(models.Model): name = models.CharField(max_length=50, unique=True) parent = models.ForeignKey('self', null=True, blank=True, related_name='children')

def __unicode__(self): return self.name

class Meta: ordering = ['tree_id', 'lft']

mptt.register(TreeNode,)

6. create a model admin that inherits from feincms TreeEditor class:

from django.contrib import admin from django.utils.translation import ugettext_lazy as _ from django.conf import settings as django_settings from feincms.admin import editor from myproject.myapp.models import *

class TreeNodeAdmin(editor.TreeEditor): pass

admin.site.register(TreeNode, TreeNodeAdmin)

End! That should be it! Let me know if I forgot something.. Here's a screenshot of the new tree-management admin page we created:

UPDATE 09/2009: how to add more actions to the tree bar. Just override the _actions_column method on the TreeNodeAdmin class, as follows::

class TreeNodeAdmin(editor.TreeEditor): def _actions_column(self, page): actions \= super(TreeNodeAdmin, self)._actions_column(page) actions.insert(0, u'<a href\="add/?parent=%s" title\="%s"><img src\="%simg/admin/icon_addlink.gif" alt\="%s"></a>' % (page.pk, _('Add child page'), settings.ADMIN_MEDIA_PREFIX , _('Add child page'))) actions.insert(0, u'<a href\="%s" title\="%s"><img src\="%simg/admin/selector-search.gif" alt\="%s" /></a>' % (page.get_absolute_url(), _('View on site'), django_settings.ADMIN_MEDIA_PREFIX, _('View on site'))) return actions

admin.site.register(TreeNode, TreeNodeAdmin