Day 75 视图类/视图工具类/工具视图类/视图集

目录

• 视图家族
  • 视图类
  • Mixins视图工具类
  • Generic工具视图类
  • 视图集

视图家族

视图类

APIView和GenericAPIView

GenericAPIView中比较重要的两个方法:

• get_object

  • 获取单查对象

• get_serializer

  • 获取单查对象的序列化

from rest_framework.generics import GenericAPIView

class CarGenericAPIView(GenericAPIView):
    # 
    queryset = models.Car.objects.filter(is_delete=False).all()
    serializer_class = serializers.CarModelSerializer
    lookup_url_kwarg = 'pk'
    def get(self, request, *args, **kwargs):
        car_obj = self.get_object()
        car_ser = self.get_serializer(car_obj)
        return APIResponse(results=car_ser.data)

GenericAPIView中query_set默认为None,需要自己进行赋值

注: models.Car.objects 是Manager对象,管理QuerySet

Mixins视图工具类

必须配合GenericAPIView类使用,将单查, 群查, 单增, 整体/局部单改, 单删留个接口封装成retrieve, list, create, update, partial_update, destroy六个方法

原因: 六个方法的实现体,调用的方法就是GenericAPIView提供的

• ListModelMixin

  群查功能源码

  class ListModelMixin:
      """
      List a queryset.
      """
      def list(self, request, *args, **kwargs):
          queryset = self.filter_queryset(self.get_queryset())
  
          page = self.paginate_queryset(queryset)
          if page is not None:
              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)
  

• RetrieveModelMixin

  单查功能源码

  class RetrieveModelMixin:
      """
      Retrieve a model instance.
      """
      def retrieve(self, request, *args, **kwargs):
          instance = self.get_object()
          serializer = self.get_serializer(instance)
          return Response(serializer.data)
  

• CreateModelMixin

  单增功能源码

  class CreateModelMixin:
      """
      Create a model instance.
      """
      def create(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)
  
      def perform_create(self, serializer):
          serializer.save()
  
      def get_success_headers(self, data):
          try:
              return {'Location': str(data[api_settings.URL_FIELD_NAME])}
          except (TypeError, KeyError):
              return {}
  

• DestroyModelMixin

  单删功能源码

  class DestroyModelMixin:
      """
      Destroy a model instance.
      """
      def destroy(self, request, *args, **kwargs):
          instance = self.get_object()
          self.perform_destroy(instance)
          return Response(status=status.HTTP_204_NO_CONTENT)
  
      def perform_destroy(self, instance):
          instance.delete()
  

• UpdateModelMixin

  整体或局部单改功能源码

  class UpdateModelMixin:
      """
      Update a model instance.
      """
      def update(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)
  
          if getattr(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)
  
      def perform_update(self, serializer):
          serializer.save()
  
      def partial_update(self, request, *args, **kwargs):
          kwargs['partial'] = True
          return self.update(request, *args, **kwargs)
  

  视图工具类的使用

  from rest_framework.mixins import RetrieveModelMixin, ListModelMixin, CreateModelMixin
  class CarReadCreateGenericAPIView(ListModelMixin, RetrieveModelMixin, CreateModelMixin, GenericAPIView):
      queryset = models.Car.objects.filter(is_delete=False).all()
      serializer_class = serializers.CarModelSerializer
      lookup_url_kwarg = 'pk'
      # 群查
      # """
      def get(self, request, *args, **kwargs):
          # car_query = self.get_queryset()
          # car_ser = self.get_serializer(car_query, many=True)
          # return APIResponse(results=car_ser.data)
          return self.list(request, *args, **kwargs)
      # """
  
      # 单查
      """
      def get(self, request, *args, **kwargs):
          # car_obj = self.get_object()
          # car_ser = self.get_serializer(car_obj)
          # return APIResponse(results=car_ser.data)
          response = self.retrieve(request, *args, **kwargs)
          return APIResponse(results=response.data)
      """
  
      # 单增
      def post(self, request, *args, **kwargs):
          return self.create(request, *args, **kwargs)
  

Generic工具视图类

工具视图类就是将不同种类的mixins与GenericAPIView进行组合,一共有9个类(九种组合)

(单查群查不能在一起)

只需要我们配置三个类属性即可: queryset, serializer_class, lookup_url_kwarg

• CreateAPIView

  class CreateAPIView(mixins.CreateModelMixin,
                      GenericAPIView):
      def post(self, request, *args, **kwargs):
          return self.create(request, *args, **kwargs)
  

• ListAPIView

  class ListAPIView(mixins.ListModelMixin,
                    GenericAPIView):
      def get(self, request, *args, **kwargs):
          return self.list(request, *args, **kwargs)
  

• RetrieveAPIView

  class RetrieveAPIView(mixins.RetrieveModelMixin,
                        GenericAPIView):
      def get(self, request, *args, **kwargs):
          return self.retrieve(request, *args, **kwargs)
  

• DestroyAPIView

  class DestroyAPIView(mixins.DestroyModelMixin,
                       GenericAPIView):
      def delete(self, request, *args, **kwargs):
          return self.destroy(request, *args, **kwargs)
  

• UpdateAPIView

  class UpdateAPIView(mixins.UpdateModelMixin,
                      GenericAPIView):
      def put(self, request, *args, **kwargs):
          return self.update(request, *args, **kwargs)
  
      def patch(self, request, *args, **kwargs):
          return self.partial_update(request, *args, **kwargs)
  

• ListCreateAPIView

  class ListCreateAPIView(mixins.ListModelMixin,
                          mixins.CreateModelMixin,
                          GenericAPIView):
      def get(self, request, *args, **kwargs):
          return self.list(request, *args, **kwargs)
  
      def post(self, request, *args, **kwargs):
          return self.create(request, *args, **kwargs)
  

• RetrieveUpdateAPIView

  class RetrieveUpdateAPIView(mixins.RetrieveModelMixin,
                              mixins.UpdateModelMixin,
                              GenericAPIView):
      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 patch(self, request, *args, **kwargs):
          return self.partial_update(request, *args, **kwargs)
  

• RetrieveDestroyAPIView

  class RetrieveDestroyAPIView(mixins.RetrieveModelMixin,
                               mixins.DestroyModelMixin,
                               GenericAPIView):
      def get(self, request, *args, **kwargs):
          return self.retrieve(request, *args, **kwargs)
  
      def delete(self, request, *args, **kwargs):
          return self.destroy(request, *args, **kwargs)
  

• RetrieveUpdateDestroyAPIView

  class RetrieveUpdateDestroyAPIView(mixins.RetrieveModelMixin,
                                     mixins.UpdateModelMixin,
                                     mixins.DestroyModelMixin,
                                     GenericAPIView):
      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 patch(self, request, *args, **kwargs):
          return self.partial_update(request, *args, **kwargs)
  
      def delete(self, request, *args, **kwargs):
          return self.destroy(request, *args, **kwargs)
  

视图集

核心: 视图集都继承了 ViewSetMixin 类,该类重写了as_view方法,相比APIView的as_view方法,额外多出了参数actions(解决如单查群查能放在同一个类中的问题)

• ViewSet

  该分支满足的接口与资源Model类关系不是特别密切:登录接口, 短信验证码接口

• GenericViewSet

  该分支严格满足资源接口,与数据库进行交互

• ModelViewSet

  能满足六大接口,只需要提供两个类属性

• ReadOnlyModelViewSet

  只满足单查群查接口

视图集产生的问题

1. 没有群增,群整体改,群局部改,群删四个接口
2. 删除操作视图集默认走的detroy方法是将资源从数据库中删除,通常是做一个字段is_delete字段修改表示删除
3. 响应的结构只有数据,没有数据状态码和状态信息

解决:

class CarModelViewSet(ModelViewSet):
    queryset = models.Car.objects.filter(is_delete=False).all()
    serializer_class = serializers.CarModelSerializer
    # 分析：从实际开发角度分析不合理点
    # 1）没有群增，群整体改，群局部改，群删四个接口
    # 2）删除操作视图集默认走的destroy方法是将资源从数据库中删除，通常一个做字段is_delete字段修改表示删除
    # 3）响应的结果只有数据，没有数据状态码和状态信息

    # 解决1,
    # 群整体改，群局部改，全删三个接口可以独立成三个方法
    def many_update(self, request, *args, **kwargs):
        request_data = request.data
        try:
            pks = []
            for dic in request_data:
                pk = dic.pop('pk')
                pks.append(pk)
            book_query = models.Car.objects.filter(is_delete=False, pk__in=pks).all()
            if len(pks) != len(book_query):
                raise Exception('pk对应的数据不存在')
        except Exception as e:
            return Response({'detail': '%s' % e}, status=400)

        car_ser = self.get_serializer(instance=book_query, data=request_data, many=True)

        car_ser.is_valid(raise_exception=True)
        car_list = car_ser.save()
        return APIResponse(results=self.get_serializer(car_list, many=True).data)
    
    def many_partial_update(self, request, *args, **kwargs):
        return APIResponse(msg='这个地方是群局部改，你会写！')
    
    def many_destroy(self, request, *args, **kwargs):
        return APIResponse(msg='这个地方是群删，你会写！')
    # 群增与单增必须公用一个接口，都要走create方法 - 重写create方法，用逻辑进行拆分
    def create(self, request, *args, **kwargs):
        request_data = request.data
        if isinstance(request_data, list):
            car_ser = self.get_serializer(data=request_data, many=True)
            car_ser.is_valid(raise_exception=True)
            car_obj = car_ser.save()
            return APIResponse(msg='群增成功', results=self.get_serializer(car_obj, many=True).data)

        return super().create(request, *args, **kwargs)


    # 解决2，destroy方法是完成is_delete字段值修改 - 重写destroy方法，自定义实现体
    def destroy(self, request, *args, **kwargs):
        car_obj = self.get_object()
        car_obj.is_delete = True
        car_obj.save()
        return APIResponse(msg='删除成功')


    # 解决3，让群查有状态码和状态信息 - 重写list方法
    def list(self, request, *args, **kwargs):
        response = super().list(request, *args, **kwargs)
        return APIResponse(results=response.data)