如何過濾Django ModelForm中的ManyToManyField選項？

Question

我想在我的ModelForm過濾ManyToManyField選擇：

class MyForm(forms.ModelForm): 
    class Meta: 
     model = Entity 
     fields = ['parent_entities'] 

    def __init__(self, *args, **kwargs): 
     self.root_entity = kwargs.pop('root_entity') 
     self.Meta.fields['parent_entities'].queryset = Entity.objects.filter(root_entity=self.root_entity) 
     super(MyForm, self).__init__(*args, **kwargs) 

我嘗試了很多不同的代碼，我已經看到了，但沒有尚未奏效。

我想我的問題是，我不能得到這個'parent_entities'字段。 有了這個代碼，我有錯誤：

list indices must be integers, not str 

Answer 1

def __init__(self, *args, **kwargs): 
    # First pop your kwargs that may bother the parent __init__ method 
    self.root_entity = kwargs.pop('root_entity') 
    # Then, let the ModelForm initialize: 
    super(MyForm, self).__init__(*args, **kwargs) 
    # Finally, access the fields dict that was created by the super().__init__ call 
    self.fields['parent_entities'].queryset = Entity.objects.filter(root_entity=self.root_entity)