def save(self, *args, **kwargs):
        """
        Set default for ``publish_date``. We can't use ``auto_now_add`` on
        the field as it will be blank when a blog post is created from
        the quick blog form in the admin dashboard.
        """
        if self.publish_date is None:
            self.publish_date = now()
        super(Displayable, self).save(*args, **kwargs)