我目前有一个项目，人们可以创建职位。我想显示一条消息，说一个帖子已成功地被投票，但SuccessMessageMixin不起作用。我已经尝试了其他方法，这是包括在我的代码，我将张贴在下面。SuccessMessageMixin适用于其他视图。我不知道为什么它不适合这个视图。
重定向代码不起作用的视图

class PostUpvoteRedirect(SuccessMessageMixin, RedirectView):
    model = Post
    success_message = "Post was upvoted successfully"
    def get_redirect_url(self, *args, **kwargs):
        obj = get_object_or_404(
            Post,
            publish__year=self.kwargs['year'],
            publish__month=self.kwargs['month'],
            publish__day=self.kwargs['day'],
            slug=self.kwargs['post'],
        )
        url_ = obj.get_absolute_url()
        user = self.request.user
        if (user != None):
            if user in obj.Upvote.all():
                obj.Upvote.remove(user)
            else:
                obj.Upvote.add(user)
                if user in obj.Downvote.all():
                    obj.Downvote.remove(user)
            success_message = "Post was upvoted successfully"
        return url_

代码在哪里工作

class PostCreateView(SuccessMessageMixin, LoginRequiredMixin, CreateView):
    model = Post
    fields = ['title','body']
    success_message = "Post was created successfully"

    def form_valid(self, form):
        form.instance.author = self.request.user
        return super().form_valid(form)