rest_framework 总流程

rest_framework 总流程

class APIView(View):

# 配置文件
renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES
parser_classes = api_settings.DEFAULT_PARSER_CLASSES
authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES
throttle_classes = api_settings.DEFAULT_THROTTLE_CLASSES
permission_classes = api_settings.DEFAULT_PERMISSION_CLASSES
content_negotiation_class = api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS
metadata_class = api_settings.DEFAULT_METADATA_CLASS
versioning_class = api_settings.DEFAULT_VERSIONING_CLASS

settings = api_settings

schema = DefaultSchema()



def dispatch(self, request, *args, **kwargs):

    """
    注释
    `.dispatch()` is pretty much the same as Django's regular dispatch,
    but with extra hooks for startup, finalize, and exception handling.
    """

    # 1，封装args，和kwargs
    self.args = args
    self.kwargs = kwargs

    # 2，封装新的request，执行self.initialize_request(request, *args, **kwargs)函数，见下面62行
    request = self.initialize_request(request, *args, **kwargs)
    self.request = request


    # 4，封装请求头
    self.headers = self.default_response_headers  # deprecate?
    # self.headers = {'Allow': 'POST, OPTIONS', 'Vary': 'Accept'}


    try:
        # 5，执行initial 方法，详见下面78行
        self.initial(request, *args, **kwargs)


        # 6，获取请求方式
        # Get the appropriate handler method，
        # http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']
        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


        # 6，处理请求方式，会首先会找自己定义的self 的['get', 'post', 'put', 'patch', 'delete']
          自己没有就基类View的['get', 'post', 'put', 'patch', 'delete']方法
        response = handler(request, *args, **kwargs)

    except Exception as exc:
        response = self.handle_exception(exc)


    # 8，返回最终的response对象
    self.response = self.finalize_response(request, response, *args, **kwargs)
    return self.response



# 3，封装request，新的Request返回值返回给步骤2
def initialize_request(self, request, *args, **kwargs):
    """
    Returns the initial request object.
    """
    parser_context = self.get_parser_context(request)

    return Request(
        request,

        # 3.1 封装解析器
        parsers=self.get_parsers(),

        # 3.2 封装auth实例化对象列表
        authenticators=self.get_authenticators(),

        # 3.3，封装实例化对象列表
        negotiator=self.get_content_negotiator(),
        parser_context=parser_context
    )


# 5，执行initial方法，这是整个drf的核心组件，
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)

    # 执行内容协商并存储请求中接受的信息
    # 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



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



    # 5.2 用户认证
    # Ensure that the incoming request is permitted
    self.perform_authentication(request)


    # 5.3 权限认证
    self.check_permissions(request)


    # 5.4 限流机制
    self.check_throttles(request)