REST-framework快速构建API--源码解析

一、APIView

通过APIView实现API的过程如下：

urls.py

　　 url(r'^books/$', views.BookView.as_view(),name="books"),
    url(r'^books/(\d+)/$', views.BookDetailView.as_view(),name="detailbook"),

views.py

class BookView(APIView):
    def get(self, request):
        book_list = Book.objects.all()
        bs = BookModelSerializers(book_list, many=True, context={'request': request})
        return Response(bs.data)

    def post(self, request):
        # post请求的数据
        bs = BookModelSerializers(data=request.data)
        if bs.is_valid():
            print(bs.validated_data)
            bs.save()  # create方法
            return Response(bs.data)
        else:
            return Response(bs.errors)

class BookDetailView(APIView):

    def get(self, request, id):

        book = Book.objects.filter(pk=id).first()
        bs = BookModelSerializers(book, context={'request': request})
        return Response(bs.data)

    def put(self, request, id):
        book = Book.objects.filter(pk=id).first()
        bs = BookModelSerializers(book, data=request.data, context={'request': request})
        if bs.is_valid():
            bs.save()
            return Response(bs.data)
        else:
            return Response(bs.errors)

    def delete(self, request, id):
        Book.objects.filter(pk=id).delete()

        return Response()

urls中，定义了两个url的请求方式：

• 通过URL：http://127.0.0.1/books/   GET/POST数据

• 通过URL：http://127.0.0.1/books/id/   GET/PUT/DELETE数据

第一种，url(r'^books/$', views.BookView.as_view(),name="books"),调用过程如下：

views.BookView.as_view()

　　1、APIView.as_view()，返回view，实际上是执行View.as_view()

　　　　2、View中的as_view()返回disptch()函数

　　　　　　3、self会从View类往上找dispatch()，在APIView类中有找到dispatch()

　　　　　　　　4、dispatch()会找get、post、put、delete等方法

　　　　　　　　　　5、在当前View下，BookView类下定义了get、post，BookDetailView类下定义了get、put、delete

　　　　　　　　　　　　6、执行当前类下的对应方法

第二种URL执行过程一样。

二、ModelView

通过ModelView实现API过程如下：

urls.py

 url(r'^authors/$', views.AuthorModelView.as_view({'get':'list','post':'create'}),name="authors"),
 url(r'^authors/$', views.AuthorModelView.as_view({'get':'retrieve','post':'update','delete':'destory'}),name="authors"),

views.py

class AuthorModelView(viewsets.ModelViewSet):
    queryset = Author.objects.all()
    serializer_class = AuthorModelSerializers
　　

执行过程如下：

1、当前类下没有as_view方法，从父类ModelViewSet中查找

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

2、ModeViewSet在mixins中没有as_view,从GenericViewSet往上找

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

3、从ViewSetMixin中找到了as_view()，实际上返回了dispatch（）

ViewSetMixin==>generics.GenericAPIView==>views.APIView==>dispatch（）

4、执行dispatch（），实际上是找get、post、put、delete等方法

5、在当前类下找到对应的方法

三、认证、权限、频率源码

通过ModelView方式实现认证,

局部应用：

class AuthorModelView(viewsets.ModelViewSet):

    authentication_classes = [TokenAuth, ]
    queryset = Author.objects.all()
    serializer_class = AuthorModelSerializers
    pagination_class = StandardResultsSetPagination

　　

　　

全局应用：

REST_FRAMEWORK={
    "DEFAULT_AUTHENTICATION_CLASSES":["app01.utils.TokenAuth",],

}

　　

源码实现过程：

服务端以authors为例：

　1、在AuthorModelView中查找as_view()，在本类中找不到，往上查找；

　2、父类：viewsets.ModelViewSet

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、其他几个父类没有as_view（）和祖父类了，只能从GenericViewSet往上找；

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、最左边父类ViewSetMixin查找as_view（），找到了

　　5、ViewSetMixin中的as_veiw()实际上返回了dispatch（）

　　6、再查找dispatch（）方法，顺序：generics.GenericAPIView==>APIView==>dispatch（）

　　

    def dispatch(self, request, *args, **kwargs):
        """
        `.dispatch()` is pretty much the same as Django's regular dispatch,
        but with extra hooks for startup, finalize, and exception handling.
        """
        self.args = args
        self.kwargs = kwargs
        request = self.initialize_request(request, *args, **kwargs)
        self.request = request
        self.headers = self.default_response_headers  # deprecate?

        try:
            self.initial(request, *args, **kwargs)

            # 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)
            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

　　7、dispatch（）中，先会执行self.initial()

    def initial(self, request, *args, **kwargs):
        """
        Runs anything that needs to occur prior to calling the method handler.
        """
        self.format_kwarg = self.get_format_suffix(**kwargs)

        # Perform content negotiation and store the accepted info on the request
        neg = self.perform_content_negotiation(request)
        request.accepted_renderer, request.accepted_media_type = neg

        # Determine the API version, if versioning is in use.
        version, scheme = self.determine_version(request, *args, **kwargs)
        request.version, request.versioning_scheme = version, scheme

        # Ensure that the incoming request is permitted
        self.perform_authentication(request)
        self.check_permissions(request)
        self.check_throttles(request)

　　8、initial（）中会对过来的请求进行认证、授权、频率检测。

图标流程如下：