URL Shortener
=============

The URL shortening has becoming a big deal of the Internet especially for
transfering long URLs.

And so many URL shortening services exist, each with his own features.

Originally Zinnia provided a only way to generate short urls for your
entries, and you needed to install *django_bitly*.

One way it's not bad, but it's not enough.

First of all Zinnia now provides his own short URLs for the entries, ex :

  http://mydomain.com/blog/1/

Of course the URL is short (and can be shorter) but if you have a long
domain, the URL can be not so short, ex :

  http://mysuperverylongdomain.com/blog/1/ (40 characters !)

But now you can easily change this behavior and use your favorite URL
shortener service by writing a backend.


Writing your own URL shortener backend
--------------------------------------

Writing a backend for using your custom URL shortener is simple as
possible, you only needs to follows 4 rules.

#. In a new python file write a function named **backend** taking an Entry
   instance in parameters.

#. The **backend** function should returns an URL including the protocol
   and the domain.

#. If the **backend** requires initial configuration you must raise a
   *django.core.exceptions.ImproperlyConfigured* exception if the
   configuration is not valid. The error will be displayed in the console.

#. Register your backend to be used in your project with this setting : ::

    ZINNIA_URL_SHORTENER_BACKEND = 'path.to.your.url.shortener.module'

Here the source code of the default backend. ::

    from django.contrib.sites.models import Site
    from django.core.urlresolvers import reverse
    from zinnia.settings import PROTOCOL

    def backend(entry):
        return '%s://%s%s' % (PROTOCOL, Site.objects.get_current().domain,
                              reverse('zinnia_entry_shortlink', args=[entry.pk]))

For a more examples take a look in this folder : *zinnia/url_shortener/backends/*.