Django-rest-framework源码分析----认证

一、基础

1.1.安装

两种方式：

github
pip直接安装

pip install djangorestframework

1.2.需要先了解的一些知识

理解下面两个知识点非常重要，django-rest-framework源码中到处都是基于CBV和面向对象的封装

（1）面向对象封装的两大特性

把同一类方法封装到类中

将数据封装到对象中

（2）CBV

基于反射实现根据请求方式不同，执行不同的方法

原理：url-->view方法-->dispatch方法（反射执行其它方法：GET/POST/PUT/DELETE等等）

二、简单实例

2.1.settings

先创建一个project和一个app(我这里命名为API)

首先要在settings的app中添加

INSTALLED_APPS = [

    'rest_framework',

]

2.2.url

from django.contrib import admin

from django.urls import path

from API.views import AuthView

urlpatterns = [

    path('admin/', admin.site.urls),

    path('api/v1/auth/',AuthView.as_view()),

]

2.3.models

一个保存用户的信息

一个保存用户登录成功后的token

from django.db import models

class UserInfo(models.Model):

    USER_TYPE = (

        (1,'普通用户'),

        (2,'VIP'),

        (3,'SVIP')

    )

    user_type = models.IntegerField(choices=USER_TYPE)

    username = models.CharField(max_length=32)

    password = models.CharField(max_length=64)

class UserToken(models.Model):

    user = models.OneToOneField(UserInfo,on_delete=models.CASCADE)

    token = models.CharField(max_length=64)

2.4.views

用户登录（返回token并保存到数据库）

from django.shortcuts import render

from django.http import JsonResponse

from rest_framework.views import APIView

from API import models

def md5(user):

    import hashlib

    import time

    #当前时间，相当于生成一个随机的字符串

    ctime = str(time.time())

    m = hashlib.md5(bytes(user,encoding='utf-8'))

    m.update(bytes(ctime,encoding='utf-8'))

    return m.hexdigest()

class AuthView(object):

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

        ret = {'code':1000,'msg':None}

        try:

            user = request._request.POST.get('username')

            pwd = request._request.POST.get('password')

            obj = models.UserInfo.objects.filter(username=user,password=pwd).first()

            if not obj:

                ret['code'] = 1001

                ret['msg'] = '用户名或密码错误'

            #为用户创建token

            token = md5(user)

            #存在就更新，不存在就创建

            models.UserToken.objects.update_or_create(user=obj,defaults={'token':token})

            ret['token'] = token

        except Exception as e:

            ret['code'] = 1002

            ret['msg'] = '请求异常'

        return JsonResponse(ret)

2.5.利用postman发请求

如果用户名和密码正确的话会生成token值，下次该用户再登录时，token的值就会更新

数据库中可以看到token的值

当用户名或密码错误时，抛出异常

三、添加认证

基于上面的例子，添加一个认证的类

3.1.url

path('api/v1/order/',OrderView.as_view()),

3.2.views

from django.shortcuts import render,HttpResponse

from django.http import JsonResponse

from rest_framework.views import APIView

from API import models

from rest_framework.request import Request

from rest_framework import exceptions

from rest_framework.authentication import BasicAuthentication

ORDER_DICT = {

    1:{

        'name':'apple',

        'price':15

    },

    2:{

        'name':'dog',

        'price':100

    }

}

def md5(user):

    import hashlib

    import time

    #当前时间，相当于生成一个随机的字符串

    ctime = str(time.time())

    m = hashlib.md5(bytes(user,encoding='utf-8'))

    m.update(bytes(ctime,encoding='utf-8'))

    return m.hexdigest()

class AuthView(object):

    '''用于用户登录验证'''

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

        ret = {'code':1000,'msg':None}

        try:

            user = request._request.POST.get('username')

            pwd = request._request.POST.get('password')

            obj = models.UserInfo.objects.filter(username=user,password=pwd).first()

            if not obj:

                ret['code'] = 1001

                ret['msg'] = '用户名或密码错误'

            #为用户创建token

            token = md5(user)

            #存在就更新，不存在就创建

            models.UserToken.objects.update_or_create(user=obj,defaults={'token':token})

            ret['token'] = token

        except Exception as e:

            ret['code'] = 1002

            ret['msg'] = '请求异常'

        return JsonResponse(ret)

class Authentication(APIView):

    '''认证'''

    def authenticate(self,request):

        token = request._request.GET.get('token')

        token_obj = models.UserToken.objects.filter(token=token).first()

        if not token_obj:

            raise exceptions.AuthenticationFailed('用户认证失败')

        #在rest framework内部会将这两个字段赋值给request，以供后续操作使用

        return (token_obj.user,token_obj)

    def authenticate_header(self, request):

        pass

class OrderView(APIView):

    '''订单相关业务'''

    authentication_classes = [Authentication,]    #添加认证

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

        #request.user

        #request.auth

        ret = {'code':1000,'msg':None,'data':None}

        try:

            ret['data'] = ORDER_DICT

        except Exception as e:

            pass

        return JsonResponse(ret)

3.3用postman发get请求

请求的时候没有带token，可以看到会显示“用户认证失败”

这样就达到了认证的效果，django-rest-framework的认证是怎么实现的呢，下面基于这个例子来剖析drf的源码。

四、drf的认证源码分析

源码流程图

请求先到dispatch

dispatch()主要做了两件事

封装request
认证

具体看我写的代码里面的注释

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

        #对原始request进行加工，丰富了一些功能

        #Request(

        #     request,

        #     parsers=self.get_parsers(),

        #     authenticators=self.get_authenticators(),

        #     negotiator=self.get_content_negotiator(),

        #     parser_context=parser_context

        # )

        #request(原始request,[BasicAuthentications对象，])

        #获取原生request,request._request

        #获取认证类的对象，request.authticators

        #1.封装request

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

        self.request = request

        self.headers = self.default_response_headers  # deprecate?

        try:

            #2.认证

            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

4.1.reuqest

（1）initialize_request()

可以看到initialize()就是封装原始request

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(),    #[BasicAuthentication(),],把对象封装到request里面了

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

（2）get_authenticators()

通过列表生成式，返回对象的列表

    def get_authenticators(self):

        """

        Instantiates and returns the list of authenticators that this view can use.

        """

        return [auth() for auth in self.authentication_classes]

（3）authentication_classes

APIView里面有个 authentication_classes 字段

可以看到默认是去全局的配置文件找（api_settings）

class APIView(View):

    # The following policies may be set at either globally, or per-view.

    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

4.2.认证

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

    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

        #对原始request进行加工，丰富了一些功能

        #Request(

        #     request,

        #     parsers=self.get_parsers(),

        #     authenticators=self.get_authenticators(),

        #     negotiator=self.get_content_negotiator(),

        #     parser_context=parser_context

        # )

        #request(原始request,[BasicAuthentications对象，])

        #获取原生request,request._request

        #获取认证类的对象，request.authticators

        #1.封装request

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

        self.request = request

        self.headers = self.default_response_headers  # deprecate?

        try:

            #2.认证

            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

（1）initial()

主要看 self.perform_authentication(request),实现认证

    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

        #3.实现认证

        self.perform_authentication(request)

        self.check_permissions(request)

        self.check_throttles(request)

（2）perform_authentication()

调用了request.user

    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

（3）user

request.user的request的位置

点进去可以看到Request有个user方法,加 @property 表示调用user方法的时候不需要加括号“user()”，可以直接调用：request.user

    @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():

                #获取认证对象，进行一步步的认证

                self._authenticate()

        return self._user

（4）_authenticate()

循环所有authenticator对象

    def _authenticate(self):

        """

        Attempt to authenticate the request using each authentication instance

        in turn.

        """

        #循环认证类的所有对象

        #执行对象的authenticate方法

        for authenticator in self.authenticators:

            try:

                #执行认证类的authenticate方法

                #这里分三种情况

                #1.如果authenticate方法抛出异常，self._not_authenticated()执行

                #2.有返回值，必须是元组：（request.user,request.auth）

                #3.返回None，表示当前认证不处理，等下一个认证来处理

                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()

返回值就是例子中的：

token_obj.user-->>request.user

token_obj-->>request.auth

#在rest framework内部会将这两个字段赋值给request，以供后续操作使用

return (token_obj.user,token_obj)     #例子中的return

当都没有返回值，就执行self._not_authenticated(),相当于匿名用户，没有通过认证

    def _not_authenticated(self):

        """

        Set authenticator, user & authtoken representing an unauthenticated request.

        Defaults are None, AnonymousUser & None.

        """

        self._authenticator = None

        if api_settings.UNAUTHENTICATED_USER:

            self.user = api_settings.UNAUTHENTICATED_USER()   #AnonymousUser匿名用户

        else:

            self.user = None

        if api_settings.UNAUTHENTICATED_TOKEN:

            self.auth = api_settings.UNAUTHENTICATED_TOKEN()  #None

        else:

            self.auth = None

面向对象知识：

子类继承父类，调用方法的时候：

优先去自己里面找有没有这个方法，有就执行自己的
只有当自己里面没有这个方法的时候才会去父类找

因为authenticate方法我们自己写，所以当执行authenticate()的时候就是执行我们自己写的认证

父类中的authenticate方法

    def authenticate(self, request):

        return (self.force_user, self.force_token)

我们自己写的

class Authentication(APIView):

    '''用于用户登录验证'''

    def authenticate(self,request):

        token = request._request.GET.get('token')

        token_obj = models.UserToken.objects.filter(token=token).first()

        if not token_obj:

            raise exceptions.AuthenticationFailed('用户认证失败')

        #在rest framework内部会将这两个字段赋值给request，以供后续操作使用

        return (token_obj.user,token_obj)

认证的流程就是上面写的，弄懂了原理，再写代码就更容易理解为什么了。

4.3.配置文件

继续解读源码

默认是去全局配置文件中找，所以我们应该在settings.py中配置好路径

api_settings源码

api_settings = APISettings(None, DEFAULTS, IMPORT_STRINGS)

def reload_api_settings(*args, **kwargs):

    setting = kwargs['setting']

    if setting == 'REST_FRAMEWORK':

        api_settings.reload()

setting中‘REST_FRAMEWORK’中找

全局配置方法：

API文件夹下面新建文件夹utils,再新建auth.py文件，里面写上认证的类

settings.py

#设置全局认证

REST_FRAMEWORK = {

    "DEFAULT_AUTHENTICATION_CLASSES":['API.utils.auth.Authentication',]   #里面写你的认证的类的路径

}

auth.py

# API/utils/auth.py

from rest_framework import exceptions

from API import models

class Authentication(object):

    '''用于用户登录验证'''

    def authenticate(self,request):

        token = request._request.GET.get('token')

        token_obj = models.UserToken.objects.filter(token=token).first()

        if not token_obj:

            raise exceptions.AuthenticationFailed('用户认证失败')

        #在rest framework内部会将这两个字段赋值给request，以供后续操作使用

        return (token_obj.user,token_obj)

    def authenticate_header(self, request):

        pass

在settings里面设置的全局认证，所有业务都需要经过认证，如果想让某个不需要认证，只需要在其中添加下面的代码：

authentication_classes = []    #里面为空，代表不需要认证

from django.shortcuts import render,HttpResponse

from django.http import JsonResponse

from rest_framework.views import APIView

from API import models

from rest_framework.request import Request

from rest_framework import exceptions

from rest_framework.authentication import BasicAuthentication

ORDER_DICT = {

    1:{

        'name':'apple',

        'price':15

    },

    2:{

        'name':'dog',

        'price':100

    }

}

def md5(user):

    import hashlib

    import time

    #当前时间，相当于生成一个随机的字符串

    ctime = str(time.time())

    m = hashlib.md5(bytes(user,encoding='utf-8'))

    m.update(bytes(ctime,encoding='utf-8'))

    return m.hexdigest()

class AuthView(APIView):

    '''用于用户登录验证'''

    authentication_classes = []    #里面为空，代表不需要认证

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

        ret = {'code':1000,'msg':None}

        try:

            user = request._request.POST.get('username')

            pwd = request._request.POST.get('password')

            obj = models.UserInfo.objects.filter(username=user,password=pwd).first()

            if not obj:

                ret['code'] = 1001

                ret['msg'] = '用户名或密码错误'

            #为用户创建token

            token = md5(user)

            #存在就更新，不存在就创建

            models.UserToken.objects.update_or_create(user=obj,defaults={'token':token})

            ret['token'] = token

        except Exception as e:

            ret['code'] = 1002

            ret['msg'] = '请求异常'

        return JsonResponse(ret)

class OrderView(APIView):

    '''订单相关业务'''

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

        # self.dispatch

        #request.user

        #request.auth

        ret = {'code':1000,'msg':None,'data':None}

        try:

            ret['data'] = ORDER_DICT

        except Exception as e:

            pass

        return JsonResponse(ret)

API/view.py代码

再测试一下我们的代码

不带token发请求

带token发请求

五、drf的内置认证

rest_framework里面内置了一些认证，我们自己写的认证类都要继承内置认证类 "BaseAuthentication"

4.1.BaseAuthentication源码：

class BaseAuthentication(object):

    """

    All authentication classes should extend BaseAuthentication.

    """

    def authenticate(self, request):

        """

        Authenticate the request and return a two-tuple of (user, token).

        """

        #内置的认证类，authenticate方法，如果不自己写，默认则抛出异常

        raise NotImplementedError(".authenticate() must be overridden.")

    def authenticate_header(self, request):

        """

        Return a string to be used as the value of the `WWW-Authenticate`

        header in a `401 Unauthenticated` response, or `None` if the

        authentication scheme should return `403 Permission Denied` responses.

        """

        #authenticate_header方法，作用是当认证失败的时候，返回的响应头

        pass

4.2.修改自己写的认证类

自己写的Authentication必须继承内置认证类BaseAuthentication

# API/utils/auth/py

from rest_framework import exceptions

from API import models

from rest_framework.authentication import BaseAuthentication

class Authentication(BaseAuthentication):

    '''用于用户登录验证'''

    def authenticate(self,request):

        token = request._request.GET.get('token')

        token_obj = models.UserToken.objects.filter(token=token).first()

        if not token_obj:

            raise exceptions.AuthenticationFailed('用户认证失败')

        #在rest framework内部会将这两个字段赋值给request，以供后续操作使用

        return (token_obj.user,token_obj)

    def authenticate_header(self, request):

        pass

4.3.其它内置认证类

rest_framework里面还内置了其它认证类，我们主要用到的就是BaseAuthentication，剩下的很少用到

六、总结

自己写认证类方法梳理

（1）创建认证类

继承BaseAuthentication --->>1.重写authenticate方法；2.authenticate_header方法直接写pass就可以（这个方法必须写）

（2）authenticate()返回值（三种）

None ----->>>当前认证不管，等下一个认证来执行
raise exceptions.AuthenticationFailed('用户认证失败') # from rest_framework import exceptions
有返回值元祖形式：（元素1，元素2） #元素1复制给request.user; 元素2复制给request.auth

（3）局部使用

authentication_classes = [BaseAuthentication,]

（4）全局使用

#设置全局认证

REST_FRAMEWORK = {

    "DEFAULT_AUTHENTICATION_CLASSES":['API.utils.auth.Authentication',]

}

源码流程

--->>dispatch

　　　　--封装request

　　　　　　　---获取定义的认证类（全局/局部），通过列表生成式创建对象　

　　　　 ---initial

　　　　　　　----peform_authentication

　　　　　　　　　-----request.user （每部循环创建的对象）