python - Django modelform 外键更新

Question

我的模型是这样的:

class Event(models.Model):
    EventId = models.UUIDField(primary_key=True)
    Winner = models.ForeignKey('Participant', on_delete=None)

class Participant(models.Model):
    ID = models.UUIDField(primary_key=True)
    Name = models.CharField()

我正在尝试在 form.py 中使用它来更新 Event 对象的现有实例

class UpdateWinner(ModelForm):
    def __init__(self, *args, **kwargs):
        e = kwargs.pop('e', '')
        super(UpdateWinner, self).__init__(*args, **kwargs)
        self.fields['Winner'] = forms.ModelChoiceField(queryset=e))

    class Meta:
        model = Event
        fields = '__all__'

在views.py中

def update_winner(request, event_id):
        if request.method == 'POST':
            form = UpdateWinner(request.POST, instance=Event.objects.get(EventId=event_id))
            if form.is_valid():

       else:
          event_par = Participant.objects.filter(some query)
          form = UpdateWinner(instance=event, e=event_par)

我确实通过打印 eventid 进行了检查，正确的值正在传递。但由于某种原因，Winner 字段导致 form.is_valid() 函数出现一些错误，并且我收到错误“'str'对象没有属性'model'”。谁能帮我一下

Answer 1

由于您在 View 中处理 POST 请求时没有提供 e kwarg，因此您的自定义 __init__ 函数设置 e = '' 。当您去定义查询集时，这会导致错误 - 该空字符串没有属性model。尝试:

class UpdateWinner(ModelForm):
    def __init__(self, *args, **kwargs):
        e = kwargs.pop('e', None)
        super(UpdateWinner, self).__init__(*args, **kwargs)
        if e is not None:
            self.fields['Winner'] = forms.ModelChoiceField(queryset=e))