Python - Django CRUD

Django CRUD (Create, Retrieve, Update, Delete)

UPDATE: The main example use Class Based Views, I also added Function Based Views version of the same thing at the end of post.

Sample Code: You can download a sample application from https://github.com/rayed/django_crud

In this post I briefly cover the step needed to create a CRUD app in Django, the steps we will need are:

    Create an App
    Create the Model
    Create the Admin Interface (optional)
    Create the View
    Define the URLs (i.e. URL to View mapping)
    Create the Templates

Create new App

From the Django project directory we will create the new app called “servers” to store our servers information:

 ./manage.py startapp servers

We will also need to register the new app in our Django project, add the app ‘server’ to the INSTALLED_APPS in your django_proj_name/settings.py:

INSTALLED_APPS = (
  :
  'servers',
  :
)

Create the Model

The model file would be servers/models.py:

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

class Server(models.Model):
    name = models.CharField(max_length=200)
    ip = models.GenericIPAddressField()
    order = models.IntegerField()

    def __unicode__(self):
        return self.name

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

After defining the model issue the command:

./manage.py syncdb

To create the table for the new model.
Admin Interface (optional)

Django will give you free CRUD interface from the admin site, just define the file servers/admin.py as:

from django.contrib import admin
from servers.models import Server

admin.site.register(Server)

The Views

We will use Django Class-based views to crete our app pages, the file servers/views.py would look like:

from django.http import HttpResponse
from django.views.generic import TemplateView,ListView
from django.views.generic.edit import CreateView, UpdateView, DeleteView
from django.core.urlresolvers import reverse_lazy

from servers.models import Server

class ServerList(ListView):
    model = Server

class ServerCreate(CreateView):
    model = Server
    success_url = reverse_lazy('server_list')
    fields = ['name', 'ip', 'order']

class ServerUpdate(UpdateView):
    model = Server
    success_url = reverse_lazy('server_list')
    fields = ['name', 'ip', 'order']

class ServerDelete(DeleteView):
    model = Server
    success_url = reverse_lazy('server_list')

Define the URLs

We need to define app URLs in the file __servers/urls.py:

from django.conf.urls import patterns, url

from servers import views

urlpatterns = patterns('',
  url(r'^$', views.ServerList.as_view(), name='server_list'),
  url(r'^new$', views.ServerCreate.as_view(), name='server_new'),
  url(r'^edit/(?P<pk>\d+)$', views.ServerUpdate.as_view(), name='server_edit'),
  url(r'^delete/(?P<pk>\d+)$', views.ServerDelete.as_view(), name='server_delete'),
)

This URLs wouldn’t work unless you include the servers/urls.py in the main URLs file django_proj_name/urls.py:

urlpatterns = patterns('',
  :
  url(r'^servers/', include('servers.urls')),
  :
)

Templates

templates/servers/server_form.html This file will be used by Edit and Update views:

<form method="post">{% csrf_token %}
    {{ form.as_p }}
    <input type="submit" value="Submit" />
</form>

templates/servers/server_list.html This file will be used by the ListView:

<h1>Servers</h1>
<ul>
    {% for server in object_list %}
    <li>{{ server.name }}  :
    <a href="{% url "server_edit" server.id %}">{{ server.ip }}</a>
    <a href="{% url "server_delete" server.id %}">delete</a>
    </li>
    {% endfor %}
</ul>

<a href="{% url "server_new" %}">New</a>

templates/servers/server_confirm_delete.html This file will be used by DeleteView:

<form method="post">{% csrf_token %}
    Are you sure you want to delete "{{ object }}" ?
    <input type="submit" value="Submit" />
</form>

Function Based View Version

The example above uses Class Based Views (or CBV for short) to implement the views, what I will cover now is how to implement the same functionality but with Function Based Views i.e. using functions instead of classes, we will be using the same templates:

servers/views.py:

from django.shortcuts import render, redirect, get_object_or_404
from django.forms import ModelForm

from servers.models import Server

class ServerForm(ModelForm):
    class Meta:
        model = Server
        fields = ['name', 'ip', 'order']

def server_list(request, template_name='servers/server_list.html'):
    servers = Server.objects.all()
    data = {}
    data['object_list'] = servers
    return render(request, template_name, data)

def server_create(request, template_name='servers/server_form.html'):
    form = ServerForm(request.POST or None)
    if form.is_valid():
        form.save()
        return redirect('server_list')
    return render(request, template_name, {'form':form})

def server_update(request, pk, template_name='servers/server_form.html'):
    server = get_object_or_404(Server, pk=pk)
    form = ServerForm(request.POST or None, instance=server)
    if form.is_valid():
        form.save()
        return redirect('server_list')
    return render(request, template_name, {'form':form})

def server_delete(request, pk, template_name='servers/server_confirm_delete.html'):
    server = get_object_or_404(Server, pk=pk)
    if request.method=='POST':
        server.delete()
        return redirect('server_list')
    return render(request, template_name, {'object':server})

servers/urls.py:

from django.conf.urls import patterns, url

from servers import views

urlpatterns = patterns('',
  url(r'^$', views.server_list, name='server_list'),
  url(r'^new$', views.server_create, name='server_new'),
  url(r'^edit/(?P<pk>\d+)$', views.server_update, name='server_edit'),
  url(r'^delete/(?P<pk>\d+)$', views.server_delete, name='server_delete'),
)

p.s. personally I prefer using FBV over CBV, the article Django’s CBVs were a mistake explains why.