QuerySet,Object没有属性id - Django

Question

我正在尝试获取django中某些对象的id,但我不断收到以下错误异常值:QuerySet; 对象没有属性ID.我在views.py中的功能

@csrf_exempt  
def check_question_answered(request):
    userID = request.POST['userID']
    markerID = request.POST['markerID']
    title=request.POST['question']
    m = Marker.objects.get(id=markerID)
    u = App_User.objects.get(id=userID) 
    print userID
    print markerID
    print title
    # userID='1'
    # markerID='1'
    # title='Hello'
    at = AttachedInfo.objects.filter(attachedMarker=m.id, title=title)
    print 'user'
    print u.id
    print 'marker'
    print m.id
    print 'att'
    print at
    #print at.id
    if(Answer.objects.filter(marker=m.id, user=u.id, attachedInfo=at.id)):
        print 'pass'
        return HttpResponse('already answered')
    else:
        print 'not'
        return HttpResponse('not answered yet') 

错误发生在此部分的if条件中(attachedInfo = at.id).我检查过,当我从条件中删除它时,一切都运行良好.

这是models.py

class AttachedInfo(models.Model):
    title = models.CharField(max_length=200)
    helpText = models.CharField(max_length=200, null=True, blank=True)
    type = models.CharField(max_length=200)
    attachedMarker = models.ForeignKey(Marker)
    answer1 = models.CharField(max_length=200, null=True, blank=True)
    answer2 = models.CharField(max_length=200, null=True, blank=True)
    answer3 = models.CharField(max_length=200, null=True, blank=True)
    answer4 = models.CharField(max_length=200, null=True, blank=True)
    correctAnswer = models.CharField(max_length=50, null=True, blank=True)
    optionalMessage = models.CharField(max_length=200, null=True, blank=True)
    def __unicode__(self):
        return self.title

class Answer(models.Model):
    user = models.ForeignKey(App_User)
    app = models.ForeignKey(App, null=True, blank=True)
    marker = models.ForeignKey(Marker)
    attachedInfo = models.ForeignKey(AttachedInfo)
    textAnswer = models.CharField(max_length=200, null=True, blank=True)
    mcqAnswer = models.CharField(max_length=200, null=True, blank=True)
    answered = models.BooleanField(default=False)
    def __unicode__(self):
        return self.attachedInfo.title

任何帮助我为什么会收到此错误？!

Answer 1

这行代码

at = AttachedInfo.objects.filter(attachedMarker=m.id, title=title)

返回的查询集

并且您正在尝试访问它的一个字段(不存在).

你可能需要的是什么

at = AttachedInfo.objects.get(attachedMarker=m.id, title=title)

Answer 2

你得到错误的原因是因为at是QuerySet一个列表.您可以执行类似的操作at[0].id或使用get而不是filter获取at对象.

希望能帮助到你!

Answer 3

在大多数情况下，您不想像这样处理不存在的对象。代替

ad[0].id

使用

get_object_or_404(AttachedInfo, attachedMarker=m.id, title=title)

这是推荐的Django 快捷方式。