DRF之视图组

• 先大概看一下这几个 视图类 的关系
  

  视图组.jpg

• 使用APIView，定义方法

  views中：
  from rest_framework.views import APIView
  
  class BookView(APIView):
      # 查看所有
      def get(self, request):
          pass
      # 添加单条
      def post(self, request):
         pass
  class SBookView(APIView):
      # 查看单条
      def get(self, request, id):
         pass
      # 更改单条
      def put(self, request, id):
          pass
      # 删除单条
      def delete(self, request, id):
          pass
  
  对应的url：
     url(r'^book/$', views.BookView.as_view()),  # 必须加上结尾符，否则匹配不到下面
     url(r'^book/(\d+)/', views.SBookView.as_view()),
  

• 进一步封装

  views1中:
  from rest_framework import generics
  # 处理增删改查查的五个类，每个类里都有各自的处理方法
  from rest_framework.mixins import ListModelMixin, CreateModelMixin, UpdateModelMixin, DestroyModelMixin, \
    RetrieveModelMixin
  
  from app01.models import Publish
  
  class PublishSerializer(serializers.ModelSerializer):
      class Meta:
          model = Publish
          fields = '__all__'
  
  
  class PublishView(ListModelMixin, CreateModelMixin, generics.GenericAPIView):  # 【APIView由这个类里继承】
      queryset = Publish.objects.all()  # 【这两个变量必须交这个名字，因为继承类里面要拿这个变量去处理】
      serializer_class = PublishSerializer
  
      def get(self, request, *args, **kwargs):
          return self.list(request, *args, **kwargs)  # 在ListModelMixin里有这个方法
  
      def post(self, request, *args, **kwargs):
          return self.create(request, *args, **kwargs)  # 在CreateModelMixin里有这个方法
    
  
  class SPublishView(UpdateModelMixin, DestroyModelMixin, RetrieveModelMixin, generics.GenericAPIView):
      queryset = Publish.objects.all()
      serializer_class = PublishSerializer
  
      def get(self,request,*args,**kwargs):
          return self.retrieve(request,*args,**kwargs)  # 在 RetrieveModelMixin里有这个方法
  
      def put(self,request,*args,**kwargs):
          return self.update(request,*args,**kwargs)  # 在 UpdateModelMixin里有这个方法
  
      def delete(self,request,*args,**kwargs):
          return self.destroy(request,*args,**kwargs)  # 在 DestroyModelMixin里有这个方法
  
  对应的url：
      url(r'^publishes/$',views1.PublishView.as_view()),
      url(r'^publishes/(?P<pk>\d+)/', views1.SPublishView.as_view()),  # 参数必须以此命名，因为函数处理时就接收这个参数
  

• 再一步封装

  views2中：
  from rest_framework import generics
  from app01.models import Author
  
  class AuthorSerializer(serializers.ModelSerializer):
      class Meta:
          model = Author
          fields = '__all__'
  
  # 简直太省了，把get和post等方法都封装进了类里。
  class AuthorsView(generics.ListCreateAPIView):  # 这个类里提供get，post两个方法
      queryset = Author.objects.all()
      serializer_class = AuthorSerializer
  
  
  class SAuthorsView(generics.RetrieveUpdateDestroyAPIView):  # 这个类提供了get/1，put/1，delete/1。3个方法
      queryset = Author.objects.all()
      serializer_class = AuthorSerializer
  # 上面两个类对之前的类又进行了封装
  
  对应的url：
      url(r'^authors/$',views2.AuthorsView.as_view()),
      url(r'^authors/(?P<pk>\d+)/', views2.SAuthorsView.as_view()),
  

• 终极封装

  views3中：
  from rest_framework.viewsets import ModelViewSet
  
  from app01.models import Author
  from app01.serializer import AuthorSerializer
  
  class AuthorsView(ModelViewSet):
      queryset = Author.objects.all()
      serializer_class = AuthorSerializer
  
  对应的url：
      url(r'^authorsss/$',views3.AuthorsView.as_view({'get':'list','post':'create'})),
      url(r'^authorsss/(?P<pk>\d+)/',views3.AuthorsView.as_view({'get':'retrieve','delete':'destroy','put':'update'}))
      # ↑上面的as_view中的参数必须以此命名
  

封装的越深，约束性越大，功能的扩展性就越差，所以最后可根据不同的业务逻辑去使用不同的方法。

• ModelViewSet源码流程

  • 1，继承ModelViewSet

    class AuthorsView(ModelViewSet):
        queryset = Author.objects.all()
        serializer_class = AuthorSerializer
    

  • 2，先进去，看看里面的结构，继承了哪些类

    class ModelViewSet(mixins.CreateModelMixin,
                 mixins.RetrieveModelMixin,
                 mixins.UpdateModelMixin,
                 mixins.DestroyModelMixin,
                 mixins.ListModelMixin,
                 GenericViewSet):
        """
        A viewset that provides default `create()`, `retrieve()`, `update()`,
        `partial_update()`, `destroy()` and `list()` actions.
        """
        pass
    

  • 3，前5个类，分别封装了几种不同的操作方法，最后一个GenericViewSet功能强大

    class GenericViewSet(ViewSetMixin, generics.GenericAPIView):
        """
        The GenericViewSet class does not provide any actions by default,
        but does include the base set of generic view behavior, such as
        the `get_object` and `get_queryset` methods.
        """
        pass
    

  • 4，左边的ViewSetMixin，有as_view方法，将方法赋给其对象

    class ViewSetMixin(object):
    # 如果使用ModelViewSet，则执行的as_view就是ViewSetMixin中的as_view方法。
        @classonlymethod
        def as_view(cls, actions=None, **initkwargs):
            # 如果没有定义，就报错，所以必须那样写。
            if not actions:
                raise TypeError("The `actions` argument must be provided when "
                                "calling `.as_view()` on a ViewSet. For example "
                                "`.as_view({'get': 'list'})`")
    
            def view(request, *args, **kwargs): 
                self = cls(**initkwargs)
                self.action_map = actions
    
                for method, action in actions.items(): # 核心代码：把参数里面的键值对，以self.method = ...的形式，变成了self的属性
                    handler = getattr(self, action)
                    setattr(self, method, handler)
    
                if hasattr(self, 'get') and not hasattr(self, 'head'):
                    self.head = self.get
    
                self.request = request
                self.args = args
                self.kwargs = kwargs
    
                return self.dispatch(request, *args, **kwargs)
    
            return csrf_exempt(view)
    

  • 5，右边的generics.GenericAPIView继承了APIView

    class GenericAPIView(views.APIView):
    

  • 6，APIView中有dispatch方法

    def dispatch(self, request, *args, **kwargs):
        self.args = args
        self.kwargs = kwargs  # 路由中传的命名参数 
        # 1，重新封装request对象
        request = self.initialize_request(request, *args, **kwargs)
        self.request = request
        self.headers = self.default_response_headers  # deprecate?
    
        try: 
            # 2，认证，权限，频率
            self.initial(request, *args, **kwargs)
            
            # 【用字符串，反射self里面对应的方法，此步之后就有了self.get/self.post】
            # Get the appropriate handler method
            if request.method.lower() in self.http_method_names:
                handler = getattr(self, request.method.lower(),
                                  self.http_method_not_allowed) # 【如果没有找到，就走这一个】
            else:
                handler = self.http_method_not_allowed
    
            response = handler(request, *args, **kwargs)
    
        except Exception as exc:
            response = self.handle_exception(exc)
    
        self.response = self.finalize_response(request, response, *args, **kwargs)
        return self.response