在Django Rest Framework中动态修改序列化器字段

我正在尝试使用django rest框架文档中描述的高级序列化程序用法. http://django-rest-framework.org/api-guide/serializers.html#advanced-serializer-usage动态修改序列化器字段

这是我的序列化程序类：

class MovieSerializer(serializers.ModelSerializer):
    moviework_work = MovieWorkSerializer(many=True) 

    def __init__(self,*args,**kwargs):
        # Don't pass the 'fields' arg up to the superclass
        dropfields = kwargs.pop('dropfields',None)

        # Instantiate the superclass normally
        super(MovieSerializer,self).__init__(*args,**kwargs)

        if dropfields:
            # Drop fields specified in the `fields` argument.
            banished = set(dropfields)
            for field_name in banished:
                self.fields.pop(field_name)
    class Meta:
        model = Movie
        fields = ('field1','field2','moviework_work')

这是我的观点

class MovieFromInterpreterViewSet(viewsets.ModelViewSet):
    queryset = Movie.objects.all()
    serializer_class = MovieSerializer(dropfields=('moviework_work',))

我收到此错误：

TypeError: 'MovieSerializer' object is not callable