Django: Obtaining the absolute URL without access to a request object

Question

I have a model like the one below. When an instance is created, I want to send out an e-mail to an interested party:

class TrainStop(models.Model):
    name = models.CharField(max_length=32)
    notify_email = models.EmailField(null=True, blank=True)

def new_stop_created(sender, instance, created, *args, **kwargs):

    # Only for new stops
    if not created or instance.id is None: return

    # Send the status link
    if instance.notify_email:
        send_mail(
            subject='Stop submitted: %s' % instance.name,
            message='Check status: %s' % reverse('stop_status', kwargs={'status_id':str(instance.id),}),
            from_email='admin@example.com',
            recipient_list=[instance.notify_email,]
        )
signals.post_save.connect(new_stop_created, sender=TrainStop)

However, the reverse call only returns the path portion of the URL. Example: /stops/9/status/. I need a complete URL like http://example.com/stops/9/status/. How would I go about retrieving the hostname and port (for test instances that do not use port 80) of the current website?

My initial thought was to make this available via a variable in settings.py that I could then access as needed. However, thought someone might have a more robust suggestion.

Answer 1

There's the sites framework, as yedpodtrzitko mentioned, but, as you mentioned, it's very much a manual setup.

There's requiring a setting in settings.py, but it's only slightly less manual than setting up sites. (It can handle multiple domains, just as well as sites and the SITE_ID setting can).

There's an idea for replacing get_absolute_url, that would make stuff like this easier, though I think its implementation suffers from the same problem (how to get the domain, scheme [http vs https], etc).

I've been toying with the idea of a middleware that examines incoming requests and constructs a "most likely domain" setting of some sort based on the frequency of the HTTP HOST header's value. Or perhaps it could set this setting on each request individually, so you could always have the current domain to work with. I haven't gotten to the point of seriously looking into it, but it's a thought.

Answer 2

For getting current site there's object Site:

If you don’t have access to the request object, you can use the get_current() method of the Site model’s manager. You should then ensure that your settings file does contain the SITE_ID setting. This example is equivalent to the previous one:

from django.contrib.sites.models import Site

def my_function_without_request():
    current_site = Site.objects.get_current()
    if current_site.domain == 'foo.com':
        # Do something
        pass
    else:
        # Do something else.
        pass

More info: http://docs.djangoproject.com/en/dev/ref/contrib/sites/