rest_framework 认证流程

一、基本流程

rest_framework框架是基于CBV基础开发的(VPIView(View)),所以基本流程与CBV流程相似

当我们的请求发来后，会走as_views,执行view里面的方法，最开始都要执行dispatch方法

urls.py
url(r'^books/$', views.BookViews.as_view())

views.py
class BookViews(APIView):
    def get(self,request,*args,**kwargs):
　　　　passdef post(self,request,*args,**kwargs):
　　　　pass

当请求进来时首先进入as_view()

APIView类中的as_view()，

class APIView(View):

    @classmethod
    def as_view(cls, **initkwargs):
        """
        Store the original class on the view function.

        This allows us to discover information about the view when we do URL
        reverse lookups.  Used for breadcrumb generation.
        """
        if isinstance(getattr(cls, 'queryset', None), models.query.QuerySet):
            def force_evaluation():
                raise RuntimeError(
                    'Do not evaluate the `.queryset` attribute directly, '
                    'as the result will be cached and reused between requests. '
                    'Use `.all()` or call `.get_queryset()` instead.'
                )
            cls.queryset._fetch_all = force_evaluation

        view = super(APIView, cls).as_view(**initkwargs)    #执行父类（view）的as_view（）
        view.cls = cls
        view.initkwargs = initkwargs

        # Note: session based authentication is explicitly CSRF validated,
        # all other authentication is CSRF exempt.
        return csrf_exempt(view)

进入原生View类中

class View(object):

    http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']

    def __init__(self, **kwargs):
        for key, value in six.iteritems(kwargs):
            setattr(self, key, value)

    @classonlymethod
    def as_view(cls, **initkwargs):
        def view(request, *args, **kwargs):
            self = cls(**initkwargs)
            if hasattr(self, 'get') and not hasattr(self, 'head'):
                self.head = self.get
            self.request = request
            self.args = args
            self.kwargs = kwargs
            return self.dispatch(request, *args, **kwargs)  #执行dispatch()(走APIView中的dispatch())
        view.view_class = cls
        view.view_initkwargs = initkwargs

        # take name and docstring from class
        update_wrapper(view, cls, updated=())

        # and possible attributes set by decorators
        # like csrf_exempt from dispatch
        update_wrapper(view, cls.dispatch, assigned=())
        return view

所以访问views中的类是先执行dispatch方法(如果自己定义了则走自己的dispatch())，然后再用调用 其他方法

APIView中的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

　　1.#执行此方法

    request = self.initialize_request(request, *args, **kwargs)   

    def initialize_request(self, request, *args, **kwargs):
        """
        Returns the initial request object.
        """
        parser_context = self.get_parser_context(request)
　　　　　#对request进行二次封装，增加了一些功能，放入到rest_framerwork中Request中
        # 原来request对象，django.core.handlers.wsgi.WSGIRequest
         # 现在的request对象，rest_framework.request.Request
        return Request(
            request,
            parsers=self.get_parsers(),
            authenticators=self.get_authenticators(),#用于用户认证,为一个列表

　　　　negotiator=self.get_content_negotiator(), parser_context=parser_context )

将这些东西前部都封装在rest_framework的Resquest中，并返回她的对象request，从这以后我们调用的request对象不再是Django提供的request对象了，而是APIView的Resquest的对象，

    self.request = request
    self.headers = self.default_response_headers  # deprecate?

    try:
　　　　　#2.处理版本信息 处理认证信息 处理权限信息 对用户的访问频率进行限制

        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.
　　　　　#版本
        version, scheme = self.determine_version(request, *args, **kwargs)
        request.version, request.versioning_scheme = version, scheme

        # Ensure that the incoming request is permitted
　　　　#认证        
　　　　self.perform_authentication(request)
　　　　#权限
        self.check_permissions(request)
　　　　#访问频率
        self.check_throttles(request)

        # Get the appropriate handler method
　　　　#3 根据用户提交的请求方法利用反射得到请求方式
        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

　　　　　#调用具体的方法做具体的操作

        response = handler(request, *args, **kwargs)

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

　　#4.将处理后的response包装

    self.response = self.finalize_response(request, response, *args, **kwargs)
    return self.response

二、处理认证的具体分析

当diapatch方法进行到第一步时，我们调用了initialize_request方法将request等封装在Request中顶返回其对象，

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

authenticators=self.get_authenticators() #用于用户认证 是一个由authentication对象组成的列表

    def get_authenticators(self):
        """
        Instantiates and returns the list of authenticators that this view can use.
        """
        return [auth() for auth in self.authentication_classes]

authentication_classes为一个authentication类组成的列表,他默认是调用

authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES

当然我们一般是自己定义或者配置到settings中，至此我们的得到authentication对象的列表，其封装在Request对象中,

接的执行第二步

#2.处理版本信息 处理认证信息 处理权限信息 对用户的访问频率进行限制
self.initial(request, *args, **kwargs)

 #2.2处理认证信息
        self.perform_authentication(request)

查看perform_authentication的源码如下

    def perform_authentication(self, request):
        """
        Perform authentication on the incoming request.

        Note that if you override this and simply 'pass', then authentication
        will instead be performed lazily, the first time either
        `request.user` or `request.auth` is accessed.
        """
        request.user

其调用了rest_framework中Request的user方法(这个方法肯定别@property装饰（静态方法）,不然的话不可能直接不加括号的调用)

from rest_framework.request import Request

Request类中的user方法

 @property
    def user(self):
        """
        Returns the user associated with the current request, as authenticated
        by the authentication classes provided to the request.
        """
        #判断当前类中是否有已经认证过的user
        if not hasattr(self, '_user'):
            #没有认证则去认证
            self._authenticate()
        #认证过了直接返回
        return self._user

注意:user中的self代表的是request对象

没认证的话执行 调用Request类中的_authenticate()方法

 def _authenticate(self):
        """
        Attempt to authenticate the request using each authentication instance
        in turn.
        """
        #遍历request对象中封装的Authentication对象
        for authenticator in self.authenticators:
            try:
                #调用Authentication对象中的authenticate方法，必须要有这个方法不然抛出异常
                #当然Authentication类一般有我们自己定义,实现这个方法就可以了
                user_auth_tuple = authenticator.authenticate(self)
            except exceptions.APIException:
                self._not_authenticated()
                raise

            if user_auth_tuple is not None:
                self._authenticator = authenticator
                self.user, self.auth = user_auth_tuple
                return

        self._not_authenticated()

局部认证

auth.py

# 局部认证
from ..models import *
from rest_framework.authentication import BaseAuthentication
from rest_framework import exceptions
class MyAuthenticate(BaseAuthentication):
    def authenticate(self,request):
        token=request._request.GET.get("token")
        print("token",token)
        user_token_obj=UserToken.objects.filter(token=token).first()
        if user_token_obj:
            # 必须返回元祖request.user=user_token_obj, request.auth=token
            return user_token_obj,token
        else:
            raise exceptions.AuthenticationFailed("校验失败")

view.py

class BookViewsSet(viewsets.ModelViewSet):
    # 认证
    authentication_classes=[MyAuthenticate]

    queryset = Book.objects.all()
    serializer_class = BookModelSerializer(序列化)

全局认证

settings.py

REST_FRAMEWORK={
    "DEFAULT_AUTHENTICATION_CLASSES": ["api.servise.auth.MyAuthenticate"],

}

auth.py

# 局部认证
from ..models import *
from rest_framework.authentication import BaseAuthentication
from rest_framework import exceptions
class MyAuthenticate(BaseAuthentication):
    def authenticate(self,request):
        token=request._request.GET.get("token")
        print("token",token)
        user_token_obj=UserToken.objects.filter(token=token).first()
        if user_token_obj:
            # 必须返回元祖request.user=user_token_obj, request.auth=token
            return user_token_obj,token
        else:
            raise exceptions.AuthenticationFailed("校验失败")

待续