如何为@extend_schema动态设置响应（基于Mixin子类Serializer）

我希望为drf_spectacular的@extend_schema动态设置响应。该Mixin被多个子类继承，不同子类的响应会因各自的Serializer而不同，因此想要动态配置响应，是否可行？

代码示例：

class Mixin:
    @extend_schema(
        request=None,
        responses={
            status.HTTP_200_OK: self.__class__.get_serializer(), # <--- self无法直接使用
            status.HTTP_204_NO_CONTENT: None,
        }
    )
    @action(detail=True, methods=['post'], url_path='decline')
    def decline(self, request, **kwargs):
        # 业务逻辑处理

我尝试过修补viewset并编写动态选择Serializer的函数，但发现响应处于静态上下文，想确认是否真的能实现动态设置？

方式一：使用extend_schema_view在类层面配置 #

drf_spectacular提供的extend_schema_view装饰器支持在类级别动态覆盖视图动作的Schema配置。你可以让Mixin仅定义基础的action方法，然后在每个子类中通过extend_schema_view指定该子类对应的响应Serializer：

from drf_spectacular.utils import extend_schema, extend_schema_view
from rest_framework import viewsets, status

class BaseDeclineMixin:
    @action(detail=True, methods=['post'], url_path='decline')
    def decline(self, request, **kwargs):
        # 通用业务逻辑处理

# 子类1：配置专属的响应Serializer
@extend_schema_view(
    decline=extend_schema(
        request=None,
        responses={
            status.HTTP_200_OK: Subclass1Serializer,
            status.HTTP_204_NO_CONTENT: None,
        }
    )
)
class Subclass1ViewSet(BaseDeclineMixin, viewsets.ModelViewSet):
    serializer_class = Subclass1Serializer

# 子类2：配置另一个响应Serializer
@extend_schema_view(
    decline=extend_schema(
        request=None,
        responses={
            status.HTTP_200_OK: Subclass2Serializer,
            status.HTTP_204_NO_CONTENT: None,
        }
    )
)
class Subclass2ViewSet(BaseDeclineMixin, viewsets.ModelViewSet):
    serializer_class = Subclass2Serializer

方式二：利用响应字段的可调用特性自动适配子类 #

drf_spectacular允许responses中的值为可调用对象，该对象会在生成Schema时接收当前视图实例作为参数。基于此，你可以编写一个动态获取Serializer的函数，让Mixin自动适配子类的serializer_class：

from drf_spectacular.utils import extend_schema
from rest_framework import status

def get_view_serializer(view):
    # 直接通过视图实例获取子类定义的Serializer
    return view.get_serializer()

class DeclineMixin:
    @extend_schema(
        request=None,
        responses={
            status.HTTP_200_OK: get_view_serializer,
            status.HTTP_204_NO_CONTENT: None,
        }
    )
    @action(detail=True, methods=['post'], url_path='decline')
    def decline(self, request, **kwargs):
        # 通用业务逻辑处理

这种方式下，无论Mixin被哪个子类继承，生成Schema时都会自动调用子类的get_serializer()方法，获取对应的序列化器作为响应Schema。

内容的提问来源于stack exchange，提问作者Andreas