Django Rest Framework学习进程(三) 使用类视图来编写API

Hello大家好，已经到了第三部分了嘻嘻嘻，这部分主要是讲如何用类视图来写API，代码会越来越简洁的，大家加油

　　1.重构函数视图(APIView)

//重构根视图,需要继承APIView这个类,我们之前利用request.method来判断请求来源是什么样是请求,然而现在，我们只需要书写对应的函数就行，如:get函数用来处理get请求,post函数用来处理post请求等。
class SnippetList(APIView):
    """
    列出所有的snippets,或创建一个新的snippet
    """
    def get(self,request,format=None):
        snippets = Snippet.objects.all()
        serializer = SnippetSerializer(snippets,many=True)
        return Response(serializer.data)

    def post(self,request,format=None):
        serilizer = SnippetSerializer(data=request.data)
        if serilizer.is_valid():
            serilizer.save()
            return Response(serilizer.data,status=status.HTTP_201_CREATED)
        return Response(serilizer.errors,status=status.HTTP_400_BAD_REQUEST)
        
//重构实例视图,你会发现,重构完后的视图也变得简洁了
class SnippetDetail(APIView):
    """
    获取,更新或删除一个snippet
    """
    def get_object(self,pk):
        try:
            return Snippet.objects.get(pk=pk)
        except Snippet.DoesNotExist:
            raise Http404

    def get(self,request,pk,format=None):
        snippet = self.get_object(pk)
        serializer = SnippetSerializer(snippet)
        return Response(serializer.data)

    def put(self,request,pk,format=None):
        snippet = self.get_object(pk)
        serializer = SnippetSerializer(snippet,data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors,status=status.HTTP_400_BAD_REQUEST)

    def delete(self,request,pk,format=None):
        snippet = self.get_object(pk)
        snippet.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)

　　2.URL的重写

//Django的类视图,需要在后面加上as_view()
urlpatterns = [
    url(r'^snippets/$', views.SnippetList.as_view()),
    url(r'^snippets/(?P<pk>[0-9]+)/$', views.SnippetDetail.as_view()),
]
urlpatterns = format_suffix_patterns(urlpatterns)

//到这里，启动项目可以发现和之前的一样

　　3.使用mixins类来重写视图

//到目前为止，我们使用的创建/获取/更新/删除操作和我们创建的任何基于模型的API视图非常相似，这些行为都是基于REST framework中的mixin类来实现的，接下来介绍如何使用mixins类来写视图
#首先导入以下依赖包
from snippets.models import Snippet
from snippets.serializers import SnippetSerializer
from rest_framework import mixins
from rest_framework import generics

//重写SnippetList类视图,在这个mixins类视图中,我们使用GenericAPIView来构建视图,并加入了ListModelMixin and CreateModelMixin.
//基类提供核心的功能,mixins类提供.list()和.create()方法
class SnippetList(mixins.ListModelMixin,
                  mixins.CreateModelMixin,
                  generics.GenericAPIView):
    queryset = Snippet.objects.all()
    serializer_class = SnippetSerializer
    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        return self.create(request, *args, **kwargs)

        
//重写SnippetDetail,在这个mixins类中加入了.retrieve() .update() .destroy()方法
class SnippetDetail(mixins.RetrieveModelMixin,
                    mixins.UpdateModelMixin,
                    mixins.DestroyModelMixin,
                    generics.GenericAPIView):
    queryset = Snippet.objects.all()
    serializer_class = SnippetSerializer

    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)

　　4.让视图变得更简洁

//通过使用mixins类，可以使我们的类视图变得更简洁，但其实还可以更简洁，因为REST框架已经提供了一组已经混合好的通用视图，使用它可以让代码更为简洁

//重写SnippetList和SnippetDetail,你会发现...这也太简洁了8.....
//其实看继承的类的源码可以发现，这些继承的类都是用mixins类来实现的

class SnippetList(generics.ListCreateAPIView):
    queryset = Snippet.objects.all()
    serializer_class = SnippetSerializer


class SnippetDetail(generics.RetrieveUpdateDestroyAPIView):
    queryset = Snippet.objects.all()
    serializer_class = SnippetSerializer