Demisauce Getting started with Django

This tutorial will walk through the creation of a simple blog using Demisauce services. First, go to Demisauce and signup (top right) on demisauce.com, OR install demisauce. Currently signups on demisauce.com are limited so send an email to the discussion group and I will enable your account.

The full source code for this application can be found on Github so you can also pull from there and view that application.

Create a Django Demo Application

Create Django App

See the documentation on Django Docs and follow the part of installing and starting a new app, and where it says to create the app polls we will actually be createing an app called blog. It is easiest to use Sqlite as the db for this demo:

python manage.py startapp blog

Install Dependencies

Install the Demisaucepy library by running:

easy_install demisaucepy

First Demisauce Service

Edit the settings.py and add the djangodemo.blog app and also add the demisaucepy.demidj (demisauce django tags).

INSTALLED_APPS = (
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',
    'demisaucepy.demidj',
    'djangodemo.blog'
)

Now, edit the settings.py to add your demisauce configuration information. First Go to your demisauce account to get your apikey, click on the “Account” (after logging in), it should look like this

Then enter that apikey, and url to your settings.py like this:

# apikey from account page, service url of demisauce server.
DEMISAUCE_APIKEY = 'a95c21ee8e64cb5ff585b5f9b761b39d7cb9a202'
DEMISAUCE_URL = 'http://localhost:4951'
# your app name, used to make your urls unique
DEMISAUCE_APPNAME = 'djangodemo'
# if you have memcached
CACHE_BACKEND = 'memcached://192.168.125.128:11211/'
#CACHE_BACKEND = 'locmem:///'

Now Create a view following the Django tuturial called simple by first adding to the urls.py:

urlpatterns = patterns('',
    (r'^simple/$', 'djangodemo.blog.views.simple'),
)

Then, add this to simple.html:

{% load demisaucetags %}

{% dsview "feedback" "badge" %}

And add this to your blog/views.py:

from django.http import HttpResponse
from django.template import loader, RequestContext
from djangodemo.blog.models import Entry

def simple(request):
    t = loader.get_template('simple.html')
    rc = RequestContext(request,{})
    return HttpResponse(t.render(rc))

and, your page should look like

So, now we have the basics of how to use a service from Demisauce. The feedback badge is an html service, to fully function it would need javascript as well.

Creating a Demisauce Mapped Service

Demisauce python library currently provides a mapping layer, to allow local model objects to be related to remote services, similar to ORM, where the service url’s are automatically generated based on this relationship. We are going to add comments to our blog entry model, but first some style.

Download a css/template from Free Css Templates and start working on the blog, add 3 new lines to the to the url.py:

urlpatterns = patterns('',
    (r'^simple/$', 'djangodemo.blog.views.simple'),
    (r'^$', 'djangodemo.blog.views.index'),
    (r'^blog/$', 'djangodemo.blog.views.index'),
    (r'^blog/view/(?P<id>\d+)', 'djangodemo.blog.views.view'),
)

Create Models

Create the Entry class, edit the blog/models.py to resemble this:

from django.db import models
from django.db.models.base import ModelBase
from django.contrib import admin
from demisaucepy.django_helper import ModelAggregatorMeta
from demisaucepy.declarative import has_a, has_many, \
    AggregateView
from django.contrib.auth.models import User

class Entry(models.Model):
    __metaclass__ = ModelAggregatorMeta
    title = models.CharField(max_length=255)
    user = models.ForeignKey(User, unique=True)
    pub_date = models.DateTimeField('date published')
    content = models.TextField()
    comments = has_many(name='comment',lazy=True,local_key='id' )
    def __unicode__(self):
        return self.title

admin.site.register(Entry)

Then run this from the command line to sync schema to DB:

python manage.py syncdb

Creating Views

And add the new methods to blog/views.py, see the source at github

def index(request):
    entry_list = Entry.objects.all().order_by('-pub_date')[:5]
    t = loader.get_template('index.html')
    rc = RequestContext(request,{
        'entry_list': entry_list,
    })
    return HttpResponse(t.render(rc))

def view(request,id=''):
    entry_list = [Entry.objects.get(id=id)]

    #for passing cookie header info
    # note this is only if you trust the destination
    Entry.comments.add_request(request.REQUEST)
    t = loader.get_template('index.html')
    rc = RequestContext(request,{
        'entry_list': entry_list,
        'show_comments':True
    })
    return HttpResponse(t.render(rc))

Now create the index.html view page.

{% extends "base.html" %}
{% load demisaucetags %}
{% block content %}
{% if entry_list %}
    {% for entry in entry_list %}
    <div class="post">
        <h1 class="title"><a href="/blog/view/{{ entry.id }}">{{ entry.title }}</a></h1>
        <p class="byline"><small>Posted on {{ entry.pub_date|date:"F d, Y" }}

            by <a href="#">admin</a> | <a href="#">Edit</a></small></p>
        <div class="entry">
            {{ entry.content }}
        </div>
        <p class="meta">
            <a href="#" class="more">Read More</a> &nbsp;&nbsp;&nbsp;
            <a href="#" class="comments">Comments (33)</a></p>
        {% if show_comments %}
            {% if entry.comments %}
                {% autoescape off %}

                {{ entry.comments.views.summary }}
                {% endautoescape %}

            {% else %}
            no comments
            {% endif %}
        {% endif %}
    </div>
    {% endfor %}

{% else %}
    <p>No entries are available.</p>
{% endif %}

{% endblock %}

The end result should be a page with comments related to entries (Entries were created in Django admin )

Output