【Django】DRF（rest_framework）的视图相关

比眉伴天荒 2022-12-09 14:58 238阅读 0赞

#### 1.两个基类 ####

##### 1.1 APIView #####

（1）APIView继承于Django的View，是REST framework提供的所有视图的基类，request参数不是Django的HttpRequeset，而是在此基础上进行了拓展，  
**request.data**：即Django的request.POST和 request.FILES  
**request.query\_params**：即Django的request.GET  
**Response**（需另外导入）：任何APIException异常都会被捕获到

##### 1.2 GenericAPIView #####

GenericAPIView继承于APIView，增加一些比较常用的通用支持方法，一般可搭配一个或多个Mixin扩展类使用

<table> 
 <thead> 
  <tr> 
   <th>支持定义的属性</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>queryset</td> 
   <td>查询集</td> 
  </tr> 
  <tr> 
   <td>serializer_class</td> 
   <td>序列化器</td> 
  </tr> 
  <tr> 
   <td>lookup_field</td> 
   <td>查询单一数据的过滤字段，默认是pk</td> 
  </tr> 
  <tr> 
   <td>lookup_url_kwarg</td> 
   <td>查询单一数据的参数关键字名称，默认与lookup_field相同</td> 
  </tr> 
  <tr> 
   <td>pagination_class</td> 
   <td>分页控制类</td> 
  </tr> 
  <tr> 
   <td>filter_backends</td> 
   <td>过滤控制后端</td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <thead> 
  <tr> 
   <th>方法</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>get_queryset(self)</td> 
   <td>获取查询集</td> 
  </tr> 
  <tr> 
   <td>get_object(self)</td> 
   <td>获取单一模型类对象</td> 
  </tr> 
  <tr> 
   <td>get_serializer(self, *args, **kwargs)</td> 
   <td>获取实例化的序列化器对象</td> 
  </tr> 
  <tr> 
   <td>get_serializer_class(self)</td> 
   <td>获取序列化器类</td> 
  </tr> 
 </tbody> 
</table>

以上方法一般配合定义的类属性使用，确保得到的是最新的结果（因为存在惰性和缓存）

举例

from rest_framework.generics import GenericAPIView
    from rest_framework.response import Response
    from .models import BookInfo
    from .serializers import BookInfoModelSerializer
    
    # re_path(r'^books/$',views.BooksView.as_view()),
    class BooksView(GenericAPIView):
        queryset = BookInfo.objects.all()
        serializer_class = BookInfoModelSerializer
    
        # 获取列表资源：GET /books/
        def get(self,request):
            books = self.get_queryset() # 即返回类属性的查询集
            serializer = self.get_serializer(instance=books,many=True)
            return Response(data=serializer.data)
    
        # 新建单一资源：POST /books/
        def post(self,request):
            serializer = self.get_serializer(data=request.data)
            if not serializer.is_valid():
                return Response(data={ "errmsg":"参数错误"},status=400)
            serializer.save()
            return Response(data=serializer.data)
    
    
    # re_path(r'^book/(?P<pk>\d+)/$',views.BookView.as_view())
    class BookView(GenericAPIView):
        queryset = BookInfo.objects.all()
        serializer_class = BookInfoModelSerializer
    
        # lookup_field = 'pk' # 该类属性默认值就是'pk' —— 默认唯一过滤依据'pk'字段
        # lookup_url_kwarg = lookup_field # 该类属性默认等于lookup_field —— 指定提取过滤字段值的分组名称
    
        # 获取单一资源：GET /books/1/
        def get(self,request, pk):
            book = self.get_object()  # 默认使用lookup_field参数来过滤queryset
            serializer = self.get_serializer(instance=book)
            return Response(data=serializer.data)
    
        # 更新单一资源（全更新）：PUT /books/1/
        def put(self, request, pk):
            book =self.get_object()
            serializer = self.get_serializer(instance=book,data=request.data)
            if not serializer.is_valid():
                return Response(data={ "errmsg":"参数错误"},status=400)
            serializer.save()
            return Response(data=serializer.data)
    
        # 更新单一资源（部分更新）：PATCH /books/1/
        def patch(self,request, pk):
            book = self.get_object()
            serializer = self.get_serializer(instance=book,data=request.data)
            if not serializer.is_valid():
                return Response({ "errmsg":"参数错误"},status=400)
            serializer.save()
            return Response(data=serializer.data)
    
        # 删除单一资源：DELETE /books/1/
        def delete(self,request,pk):
            book = self.get_object()
            book.delete()
            return Response(data=None,status=204)

#### 2.五个扩展类 ####

<table> 
 <thead> 
  <tr> 
   <th>扩展类</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>ListModelMixin</td> 
   <td>提供<code>self.list</code>方法，封装<strong>序列化多条模型类对象(列表数据)</strong> 返回的逻辑代码</td> 
  </tr> 
  <tr> 
   <td>CreateModelMixin</td> 
   <td>提供<code>self.create</code>方法，封装<strong>反序列化新建单一对象</strong>的逻辑代码</td> 
  </tr> 
  <tr> 
   <td>RetrieveModelMixin</td> 
   <td>提供<code>self.retrieve</code>方法，封装<strong>序列化返回单一资源</strong>的逻辑代码</td> 
  </tr> 
  <tr> 
   <td>UpdateModelMixin</td> 
   <td>提供<code>self.update</code>方法，封装<strong>反序列化全更新(全校验)单一资源</strong>的逻辑代码<br> 提供<code>self.partial_update</code>方法，封装<strong>反序列化部分更新(部分校验)单一资源</strong>的逻辑代码</td> 
  </tr> 
  <tr> 
   <td>DestroyModelMixin</td> 
   <td>提供<code>self.destroy</code>方法，封装<strong>反序列化删除单一资源</strong>的逻辑代码</td> 
  </tr> 
 </tbody> 
</table>

还是上面的代码，继承GenericAPIView，感觉写法太啰嗦了，我们可以继承五大拓展类，直接return封装好的方法，大大简化代码，改写如下

from rest_framework.generics import GenericAPIView
    from rest_framework.mixins import ListModelMixin, CreateModelMixin, RetrieveModelMixin, UpdateModelMixin, \
        DestroyModelMixin
    from .models import BookInfo
    from .serializers import BookInfoModelSerializer
    
    # re_path(r'^books/$',views.BooksView.as_view()),
    class BooksView(ListModelMixin,CreateModelMixin,GenericAPIView):
        queryset = BookInfo.objects.all()
        serializer_class = BookInfoModelSerializer
    
        # 获取列表资源：GET /books/
        def get(self,request):
            return self.list(request)
    
        # 新建单一资源：POST /books/
        def post(self,request):
            return self.create(request)
    
    
    # re_path(r'^book/(?P<pk>\d+)/$',views.BookView.as_view())
    class BookView(RetrieveModelMixin,UpdateModelMixin,DestroyModelMixin,GenericAPIView):
        queryset = BookInfo.objects.all()
        serializer_class = BookInfoModelSerializer
    
        # lookup_field = 'pk' # 该类属性默认值就是'pk' —— 默认唯一过滤依据'pk'字段
        # lookup_url_kwarg = lookup_field # 该类属性默认等于lookup_field —— 指定提取过滤字段值的分组名称
    
        # 获取单一资源：GET /books/1/
        def get(self,request, pk):
            return self.retrieve(request,pk)
    
        # 更新单一资源（全更新）：PUT /books/1/
        def put(self, request, pk):
            return self.update(request,pk)
    
        # 更新单一资源（部分更新）：PATCH /books/1/
        def patch(self,request, pk):
            return self.partial_update(request,pk)
    
        # 删除单一资源：DELETE /books/1/
        def delete(self,request,pk):
            return self.destroy(request,pk)

#### 3.五个子类视图 ####

<table> 
 <thead> 
  <tr> 
   <th>视图</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>ListAPIView</td> 
   <td>序列化返回<strong>列表资源</strong> <br>提供<code>self.get</code>视图方法，内部调用拓展视图<code>self.list</code>方法</td> 
  </tr> 
  <tr> 
   <td>CreateAPIView</td> 
   <td>反序列化<strong>新建单一资源</strong> <br>提供<code>self.post</code>视图方法，内部调用拓展视图<code>self.create</code>方法</td> 
  </tr> 
  <tr> 
   <td>RetrieveAPIView</td> 
   <td>序列化返回<strong>单一资源</strong> <br>提供<code>self.get</code>视图方法，内部调用拓展视图<code>self.retrieve</code>方法</td> 
  </tr> 
  <tr> 
   <td>UpdateAPIView</td> 
   <td>反序列化<strong>更新单一资源</strong> <br>提供<code>self.put</code>视图方法，内部调用拓展视图<code>self.update</code>方法 <br>提供<code>self.patch</code>视图方法，内部调用拓展视图<code>self.partial_update</code>方法</td> 
  </tr> 
  <tr> 
   <td>DestroyAPIView</td> 
   <td>反序列化<strong>删除单一资源</strong> <br>提供<code>self.delete</code>视图方法，内部调用拓展视图<code>self.destroy</code>方法</td> 
  </tr> 
 </tbody> 
</table>

还是上面的代码，继承五大扩展类的，但是代码还不够简洁，我们还可以把它进一步精简，就是通过继承五个子类视图省略用于路由的请求方法

from rest_framework.generics import ListAPIView, CreateAPIView, RetrieveAPIView, UpdateAPIView, \
        DestroyAPIView
    from .models import BookInfo
    from .serializers import BookInfoModelSerializer
    
    # 原则：一类资源，尽可能使用一个类视图封装增删改查接口；
    # 结论：Mixin几个拓展类中提供的方法定义是如何视图函数定义 —— 可以用来进行路由映射
    
    # re_path(r'^books/$',views.BooksView.as_view()),
    class BooksView(CreateAPIView,ListAPIView):
        queryset = BookInfo.objects.all()
        serializer_class = BookInfoModelSerializer
    
    # re_path(r'^book/(?P<pk>\d+)/$',views.BookView.as_view())
    class BookView(RetrieveAPIView,UpdateAPIView,DestroyAPIView):
        queryset = BookInfo.objects.all()
        serializer_class = BookInfoModelSerializer

#### 4.视图集 ####

<table> 
 <thead> 
  <tr> 
   <th>视图</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>ViewSetMixin</td> 
   <td>重写self.as_view()函数，传入字典指定请求方式映射的视图函数</td> 
  </tr> 
  <tr> 
   <td>ViewSet</td> 
   <td>继承ViewSetMixin和APIView</td> 
  </tr> 
  <tr> 
   <td>ModelViewSet</td> 
   <td>继承五大拓展类和GenericAPIView</td> 
  </tr> 
  <tr> 
   <td>GenericViewSet</td> 
   <td>继承ViewSetMixin和GenericAPIView</td> 
  </tr> 
  <tr> 
   <td>ReadOnlyModelViewSet</td> 
   <td>继承RetrieveModelMixin、ListModelMixin和GenericAPIView；提供只读接口</td> 
  </tr> 
 </tbody> 
</table>