Question

我有这个错误，我该如何解决？

get（）返回多个事件 - 它返回2！

你能帮我理解这意味着什么，也许可以提前告诉我如何避免这个错误？

MODEL

class Event (models.Model):
    name = models.CharField(max_length=100)
    date = models.DateField(default='')
    dicript = models.CharField(max_length=50, default='Описание отсутствует')
    category = models.ForeignKey(Category,on_delete=models.CASCADE)
    adress = models.TextField(max_length=300)
    user = models.ForeignKey(User,related_name="creator",null=True)
    subs = models.ManyToManyField(User, related_name='subs',blank=True)

    @classmethod
    def make_sub(cls, this_user, sub_event):
        event, created = cls.objects.get_or_create(
            user=this_user
        )
        sub_event.subs.add(this_user)

视图

def cards_detail (request,pk=None):
    # if pk:
    event_detail = Event.objects.get(pk=pk)
    subs = event_detail.subs.count()

    # else:
    #     return CardsView()
    args = {'event_detail':event_detail,'subs':subs}
    return render(request,'events/cards_detail.html',args)


class CardsView (TemplateView):`
    template_name = 'events/cards.html'

    def get (self,request):
        events = Event.objects.all()
        return render(request,self.template_name,{'events':events })

def subs_to_event (request,pk=None):

    event = Event.objects.filter(pk=pk)
    Event.make_sub(request.user,event)


    return redirect('events:cards')

Answer 1

from django.core.exceptions import ObjectDoesNotExist, MultipleObjectsReturned
try:
    instance = Instance.objects.get(name=name)
except (ObjectDoesNotExist, MultipleObjectsReturned):
    pass

如果找到多个对象，

get（）会引发MultipleObjectsReturned，更多信息here。该错误是由event_detail = Event.objects.get(pk=pk)引起的，请检查您的活动pk是否唯一。

Answer 2

基本上，cls对象在＆＃39; get_or_create（）＆＃39;的get部分获得了多个值。 get（）只返回一个对象，而filter返回一个dict（ish）。把它放在试一试/除外。所以你有：

try:
    event, created = cls.objects.get_or_create(
    user=this_user
    )
except cls.MultipleObjectsReturned:
    event = cls.objects.filter(user=this_user).order_by('id').first()

这样，如果找到多个对象，它将处理异常并将查询更改为过滤器以接收多个对象查询集。如果没有找到记录，则无需捕获Object.DoesNotExist，因为创建部件会创建新对象。

Django get（）返回了多个

2 个答案: