檢查項目是否在ManyToMany字段？

Question

考慮這一模式：

class pm_thread(models.Model): 
    subject = models.CharField(max_length=200) 
    participants = models.ManyToManyField(User) 

什麼會檢查用戶在ManyToManyField的最佳方式？例如：

thread = get_object_or_404(pm_thread, pk=thread_id) 
if not thread.participants.contains(request.user): 
    return HttpResponse("403 FORBIDDEN",status=403) 

Answer 1

可以使用in操作：

if not request.user in thread.participants.all(): 
    ...