python - 单向删除 删除 Django Channels 线程

Question

我正在尝试让用户能够从收件箱中删除与其他用户的对话。

我遵循了 Django Docs DeleteView，尽管这可能完全错误。

View .py

class InboxView(LoginRequiredMixin, ListView):
    template_name = 'chat/inbox.html'
    context_object_name = 'threads'
    def get_queryset(self):
        return Thread.objects.by_user(self.request.user).order_by('-timestamp')
        # by_user(self.request.user)

class ThreadView(LoginRequiredMixin, FormMixin, DetailView):
    template_name = 'chat/thread.html'
    form_class = ComposeForm
    success_url = '#'

    def get_queryset(self):
        return Thread.objects.by_user(self.request.user)

    def get_object(self):
        other_username  = self.kwargs.get("username")
        obj, created    = Thread.objects.get_or_new(self.request.user, other_username)
        if obj == None:
            raise Http404
        return obj

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['form'] = self.get_form()
        return context

    def post(self, request, *args, **kwargs):
        if not request.user.is_authenticated:
            return HttpResponseForbidden()
        self.object = self.get_object()
        form = self.get_form()
        if form.is_valid():
            return self.form_valid(form)
        else:
            return self.form_invalid(form)

    def form_valid(self, form):
        thread = self.get_object()
        user = self.request.user
        message = form.cleaned_data.get("message")
        ChatMessage.objects.create(user=user, thread=thread, message=message)
        return super().form_valid(form)

class ThreadDeleteView(DeleteView):
    model = Thread
    success_url = reverse_lazy('inbox')

模型.py

class ThreadManager(models.Manager):
    def by_user(self, user):
        qlookup = Q(first=user) | Q(second=user)
        qlookup2 = Q(first=user) & Q(second=user)
        qs = self.get_queryset().filter(qlookup).exclude(qlookup2).distinct()
        return qs

    # method to grab the thread for the 2 users
    def get_or_new(self, user, other_username): # get_or_create
        username = user.username
        if username == other_username:
            return None
        # looks based off of either username
        qlookup1 = Q(first__username=username) & Q(second__username=other_username)
        qlookup2 = Q(first__username=other_username) & Q(second__username=username)
        qs = self.get_queryset().filter(qlookup1 | qlookup2).distinct()
        if qs.count() == 1:
            return qs.first(), False
        elif qs.count() > 1:
            return qs.order_by('timestamp').first(), False
        else:
            Klass = user.__class__
            user2 = Klass.objects.get(username=other_username)
            if user != user2:
                obj = self.model(
                        first=user,
                        second=user2
                    )
                obj.save()
                return obj, True
            return None, False

class Thread(models.Model):
    first        = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='chat_thread_first')
    second       = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='chat_thread_second')
    updated      = models.DateTimeField(auto_now=True)
    timestamp    = models.DateTimeField(auto_now_add=True)

    objects      = ThreadManager()

    def __str__(self):
        return f'{self.id}'

    @property
    def room_group_name(self):
        return f'chat_{self.id}'

    def broadcast(self, msg=None):
        if msg is not None:
            broadcast_msg_to_chat(msg, group_name=self.room_group_name, user='admin')
            return True
        return False

带有删除按钮的 html 线程页面

<!-- Delete Thread -->
          <form action="{% url 'chat:thread_delete' user.username %}" method='post'>  {% csrf_token %}
            <button type='submit' class='btn btn-light'>
              <i class="fas fa-trash-alt" style="color:royalblue"></i>
            </button>
          </form>

url.py

app_name = 'chat'
urlpatterns = [
    path('', chat_views.InboxView.as_view(), name='inbox'),
    re_path(r"^(?P<username>[\w.@+-]+)", chat_views.ThreadView.as_view(), name='thread'),
    re_path(r"^(?P<username>[\w.@+-]+)/delete/", chat_views.ThreadDeleteView.as_view(), name='thread_delete'),
]

我不断收到错误

TypeError at /messages/userthree/delete/ cannot unpack non-iterable NoneType object

这是由 views.py 行引起的

self.object = self.get_object()
obj, created    = Thread.objects.get_or_new(self.request.user, other_username)

Answer 1

我认为这里的问题是您的 get_or_new() 方法中的 return 语句不返回元组:

if username == other_username:
    return None

这会导致 View 崩溃，因为它期望将元组解包为两个变量。返回元组应该解决:

if username == other_username:
    return None, None