Django Rest框架：动态更改嵌套对象

我使用的是

GenericForeignKey

和

ContentTypes

，如何动态更改DRF序列化程序中的嵌入对象

例如：

class FooObjectSerializer(serializers.ModelSerializer):
    """
    Represents every foo object
    """

    # 'bar=BarSerializer' if content_type is for Bar model.
    # 'baz=BazSerializer' if content_type is for Baz model.

    class Meta:
        model = models.StoreObject
        fields = ['id', 'content_type', 'object_id', 'content_object']

你能行

class FooObjectSerializer(serializers.ModelSerializer):
    # skipped

    def __init__(self, *args, **kwargs):
        super(FooObjectSerializer, self).__init__(*args, **kwargs)
        if self.instance:
            if isinstance(self.instance.content_object, Bar):
                self.fields['content_object'] = BarSerializer()
            # adjust these checks as you may wish

---

通过此方法注入的字段是否仍需要在字段数组中定义？