【Django】REST_Framework框架——Mixin类和GenericAPIView中的视图子类源码解析

一、Mixin类

提供了几种后端视图（对数据资源进行增删改查）处理流程的实现，如果需要编写的视图属于这五种，则视图可以通过继承相应的扩展类来复用代码，减少自己编写的代码量。

这五个扩展类需要搭配GenericAPIView通用视图基类来开发业务接口

1、ListModelMixin

列表视图扩展类，提供 list(request, *args, **kwargs)方法快速实现列表视图，返回200状态码。
该Mixin的list方法会对数据进行过滤和分页，如果不重写过滤和分页的方法是不会进行过滤和分页的。

源码简化

classListModelMixin:deflist(self,request,*args,**kwargs):
          queryset=self.get_queryset()
          serializer=self.get_serializer(instance=queryset,many=True)return Response(serializer.data)

源码

classListModelMixin:"""
    List a queryset.
    """deflist(self, request,*args,**kwargs):
        queryset = self.filter_queryset(self.get_queryset())

        page = self.paginate_queryset(queryset)if page isnotNone:
            serializer = self.get_serializer(page, many=True)return self.get_paginated_response(serializer.data)

        serializer = self.get_serializer(queryset, many=True)return Response(serializer.data)

2、CreateModelMixin

创建视图扩展类，提供 create(request, *args, **kwargs)方法快速实现创建资源的视图，成功返回201状态码。
如果序列化器对前端发送的数据验证失败，返回400错误；所以要对反序列化输入字段要进行验证，校验不通过提供指定的报错。

源码简化

classCreateModelMixin:defcreate(self,request,*args,**kwargs):
          serializer=self.get_serializer(data=request.data)
          serializer.is_valid(raise_exception=True)
          serializer.save()return Response(serializer.data)

源码

classCreateModelMixin:"""
    Create a model instance.
    """defcreate(self, request,*args,**kwargs):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        self.perform_create(serializer)
        headers = self.get_success_headers(serializer.data)return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)defperform_create(self, serializer):
        serializer.save()defget_success_headers(self, data):try:return{'Location':str(data[api_settings.URL_FIELD_NAME])}except(TypeError, KeyError):return{}

3、RetrieveModelMixin

详情视图扩展类，提供 retrieve(request, *args, **kwargs)方法，可以快速实现返回一个存在的数据对象。
如果存在，返回200， 否则返回404。

源码

classRetrieveModelMixin:defretrieve(self,request,*args,**kwargs):
          instance=self.get_object()
          serializer=ProjectsSerializer(instance=instance)return Response(serializer.data)

4、UpdateModelMixin

更新视图扩展类，提供 update(request, *args, **kwargs)方法，可以快速实现更新一个存在的数据对象。
同时也提供 partial_update(request, *args, **kwargs)方法，可以实现局部更新。
成功返回200，序列化器校验数据失败时，返回400错误。

源码简化

classUpdateModelMixin:defupdate(self,request,*args,**kwargs):
         obj=self.get_object()
         serializer=ProjectsSerializer(instance=obj,data=request.data)
         serializer.is_valid(raise_exception=True)
         serializer.save()return Response(serializer.data)

源码

classUpdateModelMixin:"""
    Update a model instance.
    """defupdate(self, request,*args,**kwargs):
        partial = kwargs.pop('partial',False)
        instance = self.get_object()
        serializer = self.get_serializer(instance, data=request.data, partial=partial)
        serializer.is_valid(raise_exception=True)
        self.perform_update(serializer)ifgetattr(instance,'_prefetched_objects_cache',None):# If 'prefetch_related' has been applied to a queryset, we need to# forcibly invalidate the prefetch cache on the instance.
            instance._prefetched_objects_cache ={}return Response(serializer.data)defperform_update(self, serializer):
        serializer.save()defpartial_update(self, request,*args,**kwargs):
        kwargs['partial']=Truereturn self.update(request,*args,**kwargs)

5、DestroyModelMixin

删除视图扩展类，提供 destroy(request, *args, **kwargs)方法，可以快速实现删除一个存在的数据对象。
成功返回204，不存在返回404。

源码简化

classDestroyModelMixindefdestroy(self,request,*args,**kwargs):
         obj=self.get_object()
         obj.delete()return Response({'msg':'删除数据成功'},status=204)

源码

classDestroyModelMixin:"""
    Destroy a model instance.
    """defdestroy(self, request,*args,**kwargs):
        instance = self.get_object()
        self.perform_destroy(instance)return Response(status=status.HTTP_204_NO_CONTENT)defperform_destroy(self, instance):
        instance.delete()

二、GenericAPIView的视图子类

1、CreateAPIView

提供post方法
继承关系：CreateModelMixin、GenericAPIView
使用：基本属性定义：queryset、serializer_class

classCreateAPIView(mixins.CreateModelMixin,
                    GenericAPIView):"""
    Concrete view for creating a model instance.
    """defpost(self, request,*args,**kwargs):return self.create(request,*args,**kwargs)

2、ListAPIView

提供get方法
继承关系：ListModelMixin、GenericAPIView
使用：基本属性定义：queryset、serializer_class

classListAPIView(mixins.ListModelMixin,
                  GenericAPIView):"""
    Concrete view for listing a queryset.
    """defget(self, request,*args,**kwargs):return self.list(request,*args,**kwargs)

3、RetrieveAPIView

提供get方法
继承关系：RetrieveModelMixin、GenericAPIView
使用：基本属性定义：queryset、serializer_class

classRetrieveAPIView(mixins.RetrieveModelMixin,
                      GenericAPIView):"""
    Concrete view for retrieving a model instance.
    """defget(self, request,*args,**kwargs):return self.retrieve(request,*args,**kwargs)

4、UpdateAPIView

提供put、patch方法
继承关系：UpdateModelMixin、GenericAPIView
使用：基本属性定义：queryset、serializer_class

classUpdateAPIView(mixins.UpdateModelMixin,
                    GenericAPIView):"""
    Concrete view for updating a model instance.
    """defput(self, request,*args,**kwargs):return self.update(request,*args,**kwargs)defpatch(self, request,*args,**kwargs):return self.partial_update(request,*args,**kwargs)

5、DestoryAPIView

提供delete方法
继承关系：DestoryModelMixin、GenericAPIView
使用：基本属性定义：queryset、serializer_class

classDestroyAPIView(mixins.DestroyModelMixin,
                     GenericAPIView):"""
    Concrete view for deleting a model instance.
    """defdelete(self, request,*args,**kwargs):return self.destroy(request,*args,**kwargs)

6、ListCreateAPIView

提供get、post方法
继承关系：ListModelMixin、CreateModelMixin、GenericAPIView
使用：基本属性定义：queryset、serializer_class

classListCreateAPIView(mixins.ListModelMixin,
                        mixins.CreateModelMixin,
                        GenericAPIView):"""
    Concrete view for listing a queryset or creating a model instance.
    """defget(self, request,*args,**kwargs):return self.list(request,*args,**kwargs)defpost(self, request,*args,**kwargs):return self.create(request,*args,**kwargs)

7、RetrieveUpdateAPIView

提供get、put、patch方法
继承关系：RetrieveModelMixin、UpdateModelMixin、GenericAPIView
使用：基本属性定义：queryset、serializer_class

classRetrieveUpdateAPIView(mixins.RetrieveModelMixin,
                            mixins.UpdateModelMixin,
                            GenericAPIView):"""
    Concrete view for retrieving, updating a model instance.
    """defget(self, request,*args,**kwargs):return self.retrieve(request,*args,**kwargs)defput(self, request,*args,**kwargs):return self.update(request,*args,**kwargs)defpatch(self, request,*args,**kwargs):return self.partial_update(request,*args`

8、RetrieveDestoryAPIView

提供get、delete方法
继承关系：RetrieveModelMixin、DestoryModelMixin、GenericAPIView
使用：基本属性定义：queryset、serializer_class

classRetrieveDestroyAPIView(mixins.RetrieveModelMixin,
                             mixins.DestroyModelMixin,
                             GenericAPIView):"""
    Concrete view for retrieving or deleting a model instance.
    """defget(self, request,*args,**kwargs):return self.retrieve(request,*args,**kwargs)defdelete(self, request,*args,**kwargs):return self.destroy(request,*args,**kwargs)

9、RetrieveUpdateDestoryAPIView

提供get、put、patch、delete方法
继承关系：RetrieveModelMixin、UpdateModelMixin、DestoryModelMixin、GenericAPIView
使用：基本属性定义：queryset、serializer_class

classRetrieveUpdateDestroyAPIView(mixins.RetrieveModelMixin,
                                   mixins.UpdateModelMixin,
                                   mixins.DestroyModelMixin,
                                   GenericAPIView):"""
    Concrete view for retrieving, updating or deleting a model instance.
    """defget(self, request,*args,**kwargs):return self.retrieve(request,*args,**kwargs)defput(self, request,*args,**kwargs):return self.update(request,*args,**kwargs)defpatch(self, request,*args,**kwargs):return self.partial_update(request,*args,**kwargs)defdelete(self, request,*args,**kwargs):return self.destroy(request,*args,**kwargs)