Django, how to do CRUD with django-mptt?

Question

How we can implement CRUD functionality using generic views and django-mptt ?? I've searched a lot and couldn't find a single tutorial/sample code.

Let's say we have a Course hierarchy or Category hierarchy, or similar thing ... How we can Add/Delete/Update/Read them ??

For instance I have this model:

from django.db import models
from mptt.models import MPTTModel , TreeForeignKey


class Genre(MPTTModel):
    name            = models.CharField(max_length = 50 , unique = True)
    parent          = TreeForeignKey('self' , null = True , blank = True , related_name = 'children')

    class MPTTMeta:
        order_insertion_by = ['name']

and this views.py:

from django.views.generic.list_detail import object_list
from mp.models import Genre

def genres_list(request):
    ''' Shows all of the genres '''
    return object_list(request,
            queryset = Genre.tree.all() ,
            template_name = 'genres.html' ,
            # template_object_name = 'nodes' ## Adding "nodes" variable didn't solve the problem
    )

well ... I get this error (error is in line number "5" : {% recursetree nodes %}):

Caught VariableDoesNotExist while rendering: Failed lookup for key [nodes] in u"[{'paginator': None, 'is_paginated': False, 'page_obj': None, 'nodes_list': [<Genre: Genre object>, <Genre: Genre object>, <Genre: Genre object>, <Genre: Genre object>]}, {'csrf_token': <django.utils.functional.__proxy__ object at 0x7f5bb810f090>}, {'perms': <django.utils.functional.__proxy__ object at 0x7f5bb810ff10>, 'messages': <django.contrib.messages.storage.user_messages.LegacyFallbackStorage object at 0x324af50>, 'user': ....................................

    <html>
2   
3       {% load mptt_tags %}
4       <ul>
5           {% recursetree nodes %}
6           <li>
7               {{node.name}}

Andrei Kaigorodov · Accepted Answer · 2012-07-17T07:55:00.137

Simple CRUD application with MPTT models and class-based generic views (Django 1.4 The function-based implementation has been deprecated).

Let's begin

urls.py

from django.conf.urls.defaults import patterns, include, url
from django.views.generic import DetailView, ListView, CreateView, UpdateView
from genre.models import Genre

urlpatterns = patterns('',
    url(r'detail/(?P<pk>\d+)', DetailView.as_view(model=Genre), name="genre_detail",),
    url(r'update/(?P<pk>\d+)', UpdateView.as_view(model=Genre), name="genre_update",),
    url(r'create', CreateView.as_view(model=Genre), name="genre_create",),
    url(r'list', ListView.as_view(model=Genre), name="genre_list",),
)

models.py

from django.core.urlresolvers import reverse
from django.db import models
from mptt.models import MPTTModel


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

    def get_absolute_url(self):
        return reverse('genre_detail', kwargs={'pk': self.pk, })

    class MPTTMeta:
        order_insertion_by = ['name']

templates/genre_detail.html

<html>
<body>

<div>Object: {{ object }}</div>
<div>Object's name: {{ object.name }}</div>
<div>Object's parent: {{ object.parent }}</div>

</body>
</html>

templates/genre_form.html

<html>
<body>

<form action="" method="post">
{% csrf_token %}
{{ form.as_ul }}

<button>save</button>
</form>
</body>
</html>

templates/genre_list.html

{% load mptt_tags %}
<html>
<body>
<ul class="root">
    {% recursetree object_list %}
        <li>
            {{ node.name }}
            {% if not node.is_leaf_node %}
                <ul class="children">
                    {{ children }}
                </ul>
            {% endif %}
        </li>
    {% endrecursetree %}
</ul>
</body>
</html>

and that's it.

I had some spare time today and shared this project on github https://github.com/kaygorodov/simple-crud-mptt.

How can I define my own class-based view?

genre/views.py

from django.view.generic import UpdateView
class MyCustomUpdateView(UpdateView):
    model = Genre

    def get_form_kwargs(self):
        """
        Returns the keyword arguments for instanciating the form.
        """
        kwargs = super(MyCustomUpdateView, self).get_form_kwargs()
        kwargs.update({'my_first_param_to_init_form': 1,
                      'my_second_param_to_init_form': 2,
        })
        return kwargs

genre/urls.py

url(r'update/(?P<pk>\d+)', MyCustomUpdateView.as_view(), name="genre_update",),

This is AWESOME !!! Thanks man .. I do appreciate it :) Though, I guess I have to write some wrappers around Generic views for more customization ... Big Like :) — Soask, Jul 17 '12 at 07:17
You are welcome. If You nead to customize, You can specify your own class based view, I've edited my answer to show how to do it. — Andrei Kaigorodov, Jul 17 '12 at 07:44
In my last project I used only class-based views. It's simple, fast and you get a better design. — Andrei Kaigorodov, Jul 17 '12 at 07:53
Yes , you are right, Class Based Views are better for future development. But a question on Deletion .. Say, I have a node in course structure tree (Biology -> Chapter 1 -> 1.1 Introduction). And I want to delete "Chapter 1" node and any sub nodes. How can I delete them as well? P.S. I'm new to django MPTT — Soask, Jul 17 '12 at 08:08
You can delete it and all sub nodes will be deleted too. When Django deletes an object, by default it emulates the behavior of the SQL constraint ON DELETE CASCADE -- in other words, any objects which had foreign keys pointing at the object to be deleted will be deleted along with it. [todoc](https://docs.djangoproject.com/en/dev/topics/db/queries/#deleting-objects) — Andrei Kaigorodov, Jul 17 '12 at 08:24
I've added "delete action" to [project](https://github.com/kaygorodov/simple-crud-mptt) — Andrei Kaigorodov, Jul 17 '12 at 08:43

Django, how to do CRUD with django-mptt?

1 Answers1