Python 学习笔记（十五）--Django REST Framework之Request

from rest_framework.request import Request

    """
    Wrapper allowing to enhance a standard `HttpRequest` instance.

    Kwargs:
        - request(HttpRequest). The original request instance.
        - parsers(list/tuple). The parsers to use for parsing the
          request content.
        - authenticators(list/tuple). The authenticators used to try
          authenticating the request's user.
    """

    def __init__(self, request, parsers=None, authenticators=None,
                 negotiator=None, parser_context=None):
        assert isinstance(request, HttpRequest), (
            'The `request` argument must be an instance of '
            '`django.http.HttpRequest`, not `{}.{}`.'
            .format(request.__class__.__module__, request.__class__.__name__)
        )
        ## 二次封装request,将原生request作为drf request对象的_request属性。
        self._request = request
        self.parsers = parsers or ()
        self.authenticators = authenticators or ()
        self.negotiator = negotiator or self._default_negotiator()
        self.parser_context = parser_context
        self._data = Empty
        self._files = Empty
        self._full_data = Empty
        self._content_type = Empty
        self._stream = Empty

        if self.parser_context is None:
            self.parser_context = {}
        self.parser_context['request'] = self
        self.parser_context['encoding'] = request.encoding or settings.DEFAULT_CHARSET

        force_user = getattr(request, '_force_auth_user', None)
        force_token = getattr(request, '_force_auth_token', None)
        if force_user is not None or force_token is not None:
            forced_auth = ForcedAuthentication(force_user, force_token)
            self.authenticators = (forced_auth,)

    def __getattr__(self, attr):
        """
        If an attribute does not exist on this instance, then we also attempt
        to proxy it to the underlying HttpRequest object.
        """
        try:
            return getattr(self._request, attr)  ##通过类对象的反射获取属性和方法。保证了使用新request的方式和老的一样。
        except AttributeError:
            return self.__getattribute__(attr)

    @property
    def data(self):
        if not _hasattr(self, '_full_data'):
            self._load_data_and_files()
        return self._full_data  ##是一个字典，post请求不管使用什么编码，传过来的数据，都在request.data里；get请求过来的数据，有两种获取方式：
                                ## 一是通过request.get获取；还有一种方式query_params()获取

        self._data = Empty

class Empty:
    """
    Placeholder for unset attributes.
    Cannot use `None`, as that may be a valid value.
    """
    pass

    @property
    def query_params(self): ##用于获取get请求，地址中的参数
        """
        More semantically correct name for request.GET.
        """
        return self._request.GET

            ###三大认证模块
            self.initial(request, *args, **kwargs)

    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
        ##认证组件：检验用户--游客、合法用户、非法用户
        ##游客：代表校验通过，直接进入下一步校验（权限校验）
        ##合法用户：代表校验通过，用户存储在request.user中，再进行下一步校验（权限校验）
        ##非法用户：代表校验失败，抛出异常，返回403权限异常结果。
        self.perform_authentication(request)
        ##权限组件：校验用户权限--必须登录、所有用户、登入只读游客自读、自定义用户角色
        ##认证通过，可以进入下一步校验（频率认证）
        ##认证失败，报错异常，返回403权限异常结果
        self.check_permissions(request)
        ##频率组件：限制视图接口被访问的频率次数--限制条件（IP、id、、唯一键）、频率周期时间（s、m、h）、频率次数（3/s）
        ##没有达到限制次数：正常访问接口
        ##达到限制次数：限制时间内不能访问，限制时间到达后，可以重新访问。
        self.check_throttles(request)