源码剖析Django REST framework的认证方式及自定义认证

## 源码剖析Django REST framework的认证方式 由Django的CBV模式流程，可以知道在`url匹配完成后，会执行自定义的类中的as_view方法`。 如果自定义的类中没有定义`as_view方法`，根据面向对象中类的继承可以知道，则`会执行其父类View中的as_view方法` `在Django的View的as_view方法中，又会调用dispatch方法`。 现在来看看Django restframework的认证流程 > Django restframework是基于Django的框架，所以基于CBV的模式也会执行自定义的类中的as_view方法 先新建一个项目，配置url from django.conf.urls import url from django.contrib import admin from app01 import views urlpatterns = [ url(r'^user/', views.UserView.as_view()), ] views.py文件内容 from django.shortcuts import render,HttpResponse from rest_framework.views import APIView class UserView(APIView): def get(self,request,*args,**kwargs): print(request.__dict__) print(request.user) return HttpResponse("UserView GET") def post(self,request,*args,**kwargs): return HttpResponse("UserView POST") 启动项目，用浏览器向`http://127.0.0.1:8000/user/`发送get请求  可以知道请求发送成功。现在来看看源码流程，由于UserView继承APIView，查看APIView中的as_view方法 class APIView(View): ... @classmethod def as_view(cls, **initkwargs): 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) view.cls = cls view.initkwargs = initkwargs return csrf_exempt(view) `通过super来执行APIView的父类Django的View中的as_view方法`。上一篇文章[源码解析Django CBV的本质](https://www.cnblogs.com/renpingsheng/p/9531649.html)中已经知道，View类的as_view方法会调用dispatch方法。 View类的as_view方法源码如下所示 class View(object): ... @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) ... `as_view方法中的self实际上指的是自定义的UserView这个类`，上面的代码会执行UserView类中dispatch方法。 由于UserView类中并没有定义dispatch方法，而UserView类继承自Django restframework的APIView类，所以会执行APIView类中的dispatch方法 def dispatch(self, request, *args, **kwargs): 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) 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 可以看到，`先执行initialize_request方法处理浏览器发送的request请求`。 来看看initialize_request方法的源码 def initialize_request(self, request, *args, **kwargs): """ Returns the initial request object. """ parser_context = self.get_parser_context(request) return Request( request, parsers=self.get_parsers(), authenticators=self.get_authenticators(), negotiator=self.get_content_negotiator(), parser_context=parser_context ) 在initialize_request方法里，把浏览器发送的request和restframework的处理器，认证，选择器等对象列表作为参数实例化Request类中得到新的request对象并返回，其中跟认证相关的对象就是authenticators。 def get_authenticators(self): """ Instantiates and returns the list of authenticators that this view can use. """ return [auth() for auth in self.authentication_classes] `get_authenticators方法通过列表生成式得到一个列表，列表中包含认证类实例化后的对象` 在这里，`authentication_classes来自于api_settings的配置` authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES 通过查看api_settings的源码可以知道，可以在项目的settings.py文件中进行认证相关的配置 api_settings = APISettings(None, DEFAULTS, IMPORT_STRINGS) def reload_api_settings(*args, **kwargs): setting = kwargs['setting'] if setting == 'REST_FRAMEWORK': api_settings.reload() Django restframework通过initialize_request方法对原始的request进行一些封装后实例化得到新的request对象 然后执行initial方法来处理新得到的request对象，再来看看initial方法中又执行了哪些操作 def initial(self, request, *args, **kwargs): self.format_kwarg = self.get_format_suffix(**kwargs) neg = self.perform_content_negotiation(request) request.accepted_renderer, request.accepted_media_type = neg version, scheme = self.determine_version(request, *args, **kwargs) request.version, request.versioning_scheme = version, scheme self.perform_authentication(request) self.check_permissions(request) self.check_throttles(request) 由上面的源码可以知道，在initial方法中，`执行perform_authentication来对request对象进行认证操作` def perform_authentication(self, request): request.user `perform_authentication方法中调用执行request中的user方法`，`这里的request是封装了原始request,认证对象列表，处理器列表等之后的request对象` class Request(object): ... @property def user(self): """ Returns the user associated with the current request, as authenticated by the authentication classes provided to the request. """ if not hasattr(self, '_user'): with wrap_attributeerrors(): self._authenticate() return self._user 从request中获取`_user`的值，如果获取到则执行`_authenticate方法`，否则返回`_user` def _authenticate(self): """ Attempt to authenticate the request using each authentication instance in turn. """ for authenticator in self.authenticators: try: 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 在这里`self.authenticators`实际上是`get_authenticators`方法执行完成后返回的对象列表 class Request(object): 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__) ) self._request = request self.parsers = parsers or () self.authenticators = authenticators or () ... 循环认证的对象列表,`执行每一个认证方法的类中的authenticate方法`，得到通过认证的用户及用户的口令的元组，并返回元组完成认证的流程 在`_authenticate`方法中使用了try/except方法来捕获authenticate方法可能出现的异常 如果出现异常,就调用`_not_authenticated`方法来设置返回元组中的用户及口令并终止程序继续运行 总结，Django restframework的认证流程如下图  ## Django restframework内置的认证类 在上面的项目例子中，在UsersView的get方法中，打印`authentication_classes`和`request._user`的值 class UserView(APIView): # authentication_classes = [MyAuthentication,] def get(self,request,*args,**kwargs): print('authentication_classes:', self.authentication_classes) print(request._user) return HttpResponse("UserView GET") 打印结果为 authentication_classes: [