if form.is_valid():
    obj = form.save(commit=False)
    obj.xxx = xxx
    obj.save()

news_list = News.objects.distinct('cat__name')

news_list = News.objects.values('cat__name').distinct()

def dispatch(self, request, *args, **kwargs):
# Try to dispatch to the right method; if a method doesn't exist,
# defer to the error handler. Also defer to the error handler if the
# request method isn't on the approved list.
if request.method.lower() in self.http_method_names:
    handler = getattr(self, request.method.lower(), self.http_method_not_allowed)
else:
    handler = self.http_method_not_allowed
return handler(request, *args, **kwargs)

def get(self, request, *args, **kwargs):
     pass