drf视图基类，视图扩展类和视图子类

• 两个视图基类

GenericAPIView
属性：

    	queryset    # 要序列化的数据
    	serializer_class # 序列化类
        # 了解
        lookup_field  # 通过get_object  获取单个对象的查询key值，value值是路由中传进来的
        filter_backends  # 过滤类
        pagination_class # 分页类

方法：

        get_queryset # 获取要序列化的数据
        get_object   # 根据lookup_field配置的参数获取单个对象
        get_serializer # 获取序列化类，咱们直接用的
        
        get_serializer_class # 获取序列化类，不是咱们直接用的get_serializer调用了它
        # 了解
        filter_queryset # 跟过滤有关系
        paginate_xxx    # 跟分页有关

基于APIView写5个接口

class UserView(APIView):
    def get(self, request):
        res_list = User.objects.all()
        ser = UserSerializer(instance=res_list, many=True)
        return Response(ser.data)
 
    def post(self, request):
        ser = UserSerializer(data=request.data)
        if ser.is_valid():
            ser.save()
            return Response({'code': 100, 'msg': "新增成功"}, status=201)
        else:
            return Response({'code': 101, 'msg': ser.errors})
 
 
class UserDetailView(APIView):
    def get(self, request, pk):
        obj = User.objects.filter(pk=pk).first()
        ser = UserSerializer(instance=obj)
        return Response(ser.data)
 
    def put(self, request, pk):
        obj = User.objects.filter(pk=pk).first()
        ser = UserSerializer(instance=obj, data=request.data)
        if ser.is_valid():
            ser.save()
            return Response({'code': 100, 'msg': "修改成功"}, status=201)
        else:
            return Response({'code': 101, 'msg': ser.errors})
 
    def delete(self, request, pk):
        User.objects.filter(pk=pk).delete()
        return Response('')

** 基于GenericAPIView写5个接口**

class UserView(GenericAPIView):
    # 配置两个 类属性
    queryset = User.objects.all()
    serializer_class = UserSerializer
 
    # def get_queryset(self):
    #     if self.request.method=='GET':
    #         return User.objects.all()
    #     else:
    #         return Publish.object.all()
 
    def get(self, request):
        res_list = self.get_queryset()  # 提高扩展性
        ser = self.get_serializer(instance=res_list, many=True)
        return Response(ser.data)
 
    def post(self, request):
        ser = self.get_serializer(data=request.data)
        if ser.is_valid():
            ser.save()
            return Response({'code': 100, 'msg': "新增成功"}, status=201)
        else:
            return Response({'code': 101, 'msg': ser.errors})
 
 
class UserDetailView(GenericAPIView):
    queryset = User.objects.all()
    serializer_class = UserSerializer
 
    def get(self, request, pk):
        # obj = self.get_queryset().filter(pk=pk).first()
        # queryset.get({'pk':'有名分组分出来的'}
        obj = self.get_object()  # 根据传入的pk，获取一条数据
        ser = self.get_serializer(instance=obj)
        return Response(ser.data)
 
    def put(self, request, pk):
        obj = self.get_object()
        ser = self.get_serializer(instance=obj, data=request.data)
        if ser.is_valid():
            ser.save()
            return Response({'code': 100, 'msg': "修改成功"}, status=201)
        else:
            return Response({'code': 101, 'msg': ser.errors})
 
    def delete(self, request, pk):
        self.get_queryset().filter(pk=pk).delete()
        return Response('')

• 5个视图扩展类

基于GenericAPIView+5个视图扩展类写接口

### 必须配合GenericAPIView使用，不能配合APIView使用
from rest_framework.mixins import RetrieveModelMixin, CreateModelMixin, UpdateModelMixin, DestroyModelMixin, \
    ListModelMixin
 
 
# RetrieveModelMixin:写了一个Create方法，就是原来咱们post中的代码
# RetrieveModelMixin：retrieve，就是咱们原来的get
# UpdateModelMixin：update方法，就是咱们原来的put
# ListModelMixin：list方法，就是原来咱们的get
# DestroyModelMixin：destroy方法，就是原来咱们的delete
 
class UserView(GenericAPIView, ListModelMixin, CreateModelMixin):
    # 配置两个 类属性
    queryset = User.objects.all()
    serializer_class = UserSerializer
 
    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)
 
    def post(self, request, *args, **kwargs):
        return self.create(request, *args, **kwargs)
 
 
class UserDetailView(GenericAPIView, RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin):
    queryset = User.objects.all()
    serializer_class = UserSerializer
 
    def get(self,request, *args, **kwargs):
        return self.retrieve(request, *args, **kwargs)
 
    def put(self, request, *args,**kwargs):
        return self.update(request,*args,**kwargs)
 
    def delete(self, request, *args,**kwargs):
        return self.destroy(request,*args,**kwargs)

• 9个视图子类

基于9个视图子类写接口

from rest_framework.generics import ListAPIView,CreateAPIView,   RetrieveAPIView,DestroyAPIView,UpdateAPIView
from rest_framework.generics import ListCreateAPIView,     RetrieveUpdateDestroyAPIView,RetrieveUpdateAPIView,RetrieveDestroyAPIView
# 正常来讲  Destroy+Update 应该有一个  ，作者没加
class UserView(ListCreateAPIView):
    # 配置两个 类属性
    queryset = User.objects.all()
    serializer_class = UserSerializer
class UserDetailView(RetrieveUpdateDestroyAPIView):
    queryset = User.objects.all()
    serializer_class = UserSerializer

• 视图集

继承ModelViewSet编写5个接口

## 视图类
from rest_framework.viewsets import ModelViewSet,ReadOnlyModelViewSet
class UserView(ModelViewSet):
    queryset = User.objects.all()
    serializer_class = UserSerializer
 
## 路由
path('user/', views.UserView.as_view({'get': 'list', 'post': 'create'})),
path('user/<int:pk>', views.UserView.as_view({'get': 'retrieve', 'put': 'update', 'delete': 'destroy'})),

源码分析ViewSetMixin

@classonlymethod
def as_view(cls, actions=None, **initkwargs):
    # 路由中as_view中必须传参数，必须传字典：{'get': 'list', 'post': 'create'}
    if not actions: 
        raise TypeError("The `actions` argument must be provided when "
                        "calling `.as_view()` on a ViewSet. For example "
                        "`.as_view({'get': 'list'})`")
	# 路由匹配成功，执行view(request)，request是老的request
    def view(request, *args, **kwargs):
	    # actions={'get': 'list', 'post': 'create'}
        for method, action in actions.items():
            # method:get      action:list
            # self 是视图类的对象中通过反射，查找list，
            # handler视图类中的list方法
            handler = getattr(self, action)
            # 向视图类的对象中，反射 method:get,handler:list方法
            # self.get=list
            setattr(self, method, handler)
        return self.dispatch(request, *args, **kwargs)
    return csrf_exempt(view)
 
 
# 只要继承了ViewSetMixin，以后路由写法变量，都要协程：views.UserView.as_view({'get': 'list', 'post': 'create'}))
# 这样写好以后，对应的请求方式来了，就会执行配置的方法
 
 
# 扩展：
	-以后只要继承了ViewSetMixin，视图类中可以写任意名字的方法，不用非得写get，post，delete