docs: def get_qualified_file_url(self, field_name='file'):
          """Returns a fully qualified URL for the :attr:`file` field, including
          protocol, domain and port. In most cases, you can just use ``file.url``
          instead, which (depending on your ``MEDIA_URL``) may or may not contain
          the domain. In some cases however, you always need a fully qualified
          URL. This includes, for instance, embedding a flash video player from a
          remote domain and passing it a video URL.
          """
          url = getattr(self, field_name).url
          if '://' in url:
              # `MEDIA_URL` already contains domain
              return url
          protocol = getattr(settings, 'PROTOCOL', 'http')
          domain = Site.objects.get_current().domain
          port = getattr(settings, 'PORT', '')
          return '%(protocol)s://%(domain)s%(port)s%(url)s' % {
              'protocol': 'http',
              'domain': domain.rstrip('/'),
              'port': ':'+port if port else '',
              'url': url,
      }