views.py

class RingtoneDetailView(SingleObjectTemplateResponseMixin, ChooseTemplateMixin, SingleObjectMixin, FormMixin, TemplateResponseMixin, ProcessFormView):
    model = Ringtone
    form_class = RingtoneForm

    def dispatch(self, *args, **kwargs):
        request = args[0]
        device_info = choose_site(request)
        self.site_type = device_info['site_type']
        self.device = device_info['device']
        return super(RingtoneDetailView, self).dispatch(*args, **kwargs)

    def get(self, request, *args, **kwargs):
        self.object = self.get_object()
        
        if self.device != 'iPhone':
            return self.direct_download()
        return super(RingtoneDetailView, self).get(request, *args, **kwargs)

    def direct_download(self):
        filename = self.object.mp3.file.name
        response = HttpResponse(open(filename).read(), 'audio/mp3')
        response['Content-Disposition'] = 'attachment; filename=%s' % \
            os.path.basename(filename)
        response['Content-Length'] = os.path.getsize(filename)
        return response