def preview(request, key):
    short_url = get_shorturl_or_404(key)
    shorturl_preview.send(sender=None, short_url_id=short_url.id, request=request)
    return render(request, 'urlshortener/preview.html', {'short_url': short_url, 'current_site': RequestSite(request)})
def redirect(request, key):
    short_url = get_shorturl_or_404(key)
    shorturl_redirect.send(sender=None, short_url_id=short_url.id, request=request)
    return HttpResponsePermanentRedirect(short_url.url)