Subclassing Publishable

Due to the fact that Publishable is common Django model, it is possible to simply extend it with your custom model. When doing this, you effectively adding your custom model to whole Ella machinery and all publishing-related stuff is ready for you out-of-the box!

Let’s have a look at real-world example. During this walkthrough, we will try to create a publishable video that will have YouTube video code as source. We will keep it simple and use YouTube’s video player to show the video itself.

The very first step is to create your own application using the standard Django way:

django-admin.py startapp video

After creating the app to hold it, let’s define the class itself. If you are acustomed to Django models, this is going to look very familiar to you.:

# in models.py within your video application

from django.db import models
from django.utils.translation import ugettext_lazy as _

from ella.core.models import Publishable

class YoutubeVideo(Publishable):
    code = models.CharField(max_length=20, title=_('Code'))

    class Meta:
        verbose_name = _('Youtube video')
        verbose_name_plural = _('Youtube videos')

    def __unicode__(self):
        return self.code

Note

If you want to examine whats is going on behind the scenes when subclassing Django models, have a look at Django model inheritance. We are using Multi-table inheritance so that each Publishable subclass has a hidden pointer - publishable_ptr - to the Publishable object. This pointer also acts as PK in the DB table.

Next step is to put the new app to the settings.:

INSTALLED_APPS = (
    'ella.core',
    'ella.articles',
    ...
    'yourproject.video',
)

Finally, resync your database so the DB table for the class is created:

django-admin.py syncdb

By defining this, we already have a working publishable object, nothing more is needed. Of course, in real world, you would probably need to do some polishing (adding better title, etc.), but for now, this is enough.