Django框架（十九）--Django rest_framework-认证组件

一、什么是认证

只有认证通过的用户才能访问指定的url地址，比如：查询课程信息，需要登录之后才能查看，没有登录，就不能查看，这时候需要用到认证组件

二、利用token记录认证过的用户

1、什么是token

token是服务端生成的一串字符串，以作客户端进行请求的一个令牌，当第一次登录后，服务器生成一个Token便将此Token返回给客户端，以后客户端只需带上这个Token前来请求数据即可，无需再次带上用户名和密码。session的存储是需要空间的，session的传输一般都是通过cookie来传输，或url重写的方式。
token在服务器时可以不用存储用户信息的，token传递的方式也不限于cookie传递，token也可以保存起来

2、token的原理

当第一次登录认证过后，就会返回一个token到前台，前台之后发送请求，就会带上这个token字符串，

3、cookie、session、token的区别

cookie是保存在浏览器，以key:value的形式传递到服务器认证用户，用户名密码可能裸露，不安全

session是保存在服务器，产生随机字符串与用户信息对应，将随机字符串放在cookie中。服务器会保存一份，可能保存到缓存/数据库/文件

token发送请求的对象可以是浏览器，也可以是移动端。服务器不需要记录任何东西，每次都是一个无状态的请求，每次都是通过解密来验证是否合法

三、drf的认证组件

# 用户信息表
class UserInfo(models.Model):
    name = models.CharField(max_length=32)
    pwd = models.CharField(max_length=32)

# 用户token
class UserToken(models.Model):
    token = models.CharField(max_length=64)
    user = models.OneToOneField(to=UserInfo)

1、基本使用

from rest_framework.authentication import BaseAuthentication
from rest_framework.exceptions import APIException
from app01 import models

# 定义一个认证类
class LoginAuth(BaseAuthentication):
    # 重写authenticate方法
    def authenticate(self, request):
        # 从路由中获取token，从request对象中获取，如果token放在header中
        # query_params 是Request封装的原生request.GET
        token = request.query_params.get('token')
        ret = models.UserToken.objects.filter(token=token).first()
        if ret:
            # 能查到,说明认证通过,返回空，或者返回当前的用户对象
            # ret.user就是当前登录用户对象,一旦retrun了,后面的认证类都不执行了
            return ret.user,ret
        # 如果查不到，抛出异常
        raise APIException('用户认证失败')
        

# view 层
from rest_framework.views import APIView
# 获取随机字符串——token
def get_token(name):
    md = hashlib.md5()
    md.update(str(name).encode('utf-8'))
    return md.hexdigest()
# 用户登录
class Login(APIView):
    def post(self, request, *args, **kwargs):
        response = {'status': 100, 'msg': '登录成功'}
        name = request.data.get('name')
        pwd = request.data.get('pwd')
        ret = models.UserInfo.objects.filter(name=name, pwd=pwd).first()
        if ret:
            token = get_token(name)
            # 一旦用户信息校验通过，就产生一个token保存在Token表中
            models.UserToken.objects.create(token=token, user=ret)
            response['token'] = token
        else:
            response['status'] = 101
            response['msg'] = '用户名或密码错误'
        return JsonResponse(response, safe=False)

# 查看所有图书信息    
class Book(APIView):
    # 指定authentication_classes，会循环列表实例化，进行认证
    # 该方法是局部使用认证
    authentication_classes = [UserAuth.UserAuth, ]

    def get(self, request, *args, **kwargs):
        response = {'status': 100, 'msg': '查询成功'}
        ret = models.Book.objects.all()
        ser = MySerializer.BookSerializer(instance=ret, many=True)
        response['data'] = ser.data
        return JsonResponse(response, safe=False)

2、全局使用、局部使用、局部禁用认证

（1）全局使用

• 在settings文件中配置，配置完以后，就无需在视图类中写，已经是所有视图类都需要认证
• 必须为REST_FRAMEWORK，key值必须为DEFAULT_AUTHENTICATION_CLASSES

REST_FRAMEWORK={
    'DEFAULT_AUTHENTICATION_CLASSES':['app01.MyAuth.LoginAuth',],
}

（2）局部使用

在需要使用的视图类中写，只对当前视图类起认证作用，重新定义authentication_classes

class Book(APIView):
    # 该方法是局部使用认证
    authentication_classes = [UserAuth.UserAuth, ]

    def get(self, request, *args, **kwargs):
        response = {'status': 100, 'msg': '查询成功'}
        ret = models.Book.objects.all()
        ser = MySerializer.BookSerializer(instance=ret, many=True)
        response['data'] = ser.data
        return JsonResponse(response, safe=False)

（3）局部禁用

在配置过全局认证以后，有些视图类不需要认证，可以局部禁用认证，只需将authentication_classes定义为空列表即可。例如：登录视图，不应该有认证，就可以局部禁用

# settings中
REST_FRAMEWORK={
    'DEFAULT_AUTHENTICATION_CLASSES':['app01.MyAuth.LoginAuth',],
}

# view的视图类中
class Book(APIView):
    # 该方法是局部使用认证
    authentication_classes = []

    def get(self, request, *args, **kwargs):
        response = {'status': 100, 'msg': '查询成功'}
        ret = models.Book.objects.all()
        ser = MySerializer.BookSerializer(instance=ret, many=True)
        response['data'] = ser.data
        return JsonResponse(response, safe=False)

3、不存数据库的token实现认证

# 登录以后，会产生一个随机字符串，返回到移动端/PC端，下一次发送请求，就在后面拼上  ?token=asdfasdgasdg|{"id":1}，这样只要将后面的id通过加密获取随机字符串，与原字符串比较是否一致即可，不用再讲token存到数据库
def check_token(token):
    user = None
    ret = True
    try:
        # token 拿到的是  ‘fsdfasdfasd|{"name": "lqz", "id": 1}’
        ll = token.split('|')
        md = haslib.md5()
        md.update(ll[1].encode('utf-8'))
        md5.update(settings.password.encode('utf-8'))
        hex = md.hexdigest()
        if hex == ll[0]:
            user = ll[1]
        else:
            ret = False
     except Exception as e:
        ret = False
     return ret,user


class LoginAuth(BaseAuthentication):
    # 重写authenticate方法
    def authenticate(self, request):
        token = request.query_params.get('token')
        ret, user_info = check_token(token)
        if ret:
            return user_info, None
        # 如果查不到,抛异常
        raise exceptions.APIException('您认证失败')

def create_token(user_id):
    md5 = hashlib.md5()
    md5.update(user_id.encode('utf-8'))
    # 加盐加密
    md5.update(settings.password.encode('utf-8'))
    hex = md5.hexdigest()
    # 加密完以后，直接在后面拼上id，用于认证，传过来的id加密以后是否和原token一致
    token = hex + '|' + user_id
    print(token)
    return token


# 登录
# 产生随机字符串的时候就不需要存到数据库中
class Login(APIView):
    authentication_classes = []

    def post(self, request, *args, **kwargs):
        response = {'status': 100, 'msg': '登录成功'}
        name = request.data.get('name')
        pwd = request.data.get('pwd')
        try:
            user = models.UserInfo.objects.get(name=name, pwd=pwd)
            user_info_json = json.dumps({'name': user.name, 'id': user.pk})
            # 生产dafgasdewf|{'name':user.name,'id':user.pk}的token
            token = create_token(str(user.pk))
            response['token'] = token
        except ObjectDoesNotExist as e:
            response['status'] = 101
            response['msg'] = '用户名或密码错误'
        except Exception as e:
            response['status'] = 102
            # response['msg']='未知错误'
            response['msg'] = str(e)
        return JsonResponse(response, safe=False)

四、源码分析

as_view ----------> view -------------> dispatch -------> Request包装新的request ------> 认证、权限、频率 --------> 根据请求方式分发到不同的方法

url(r'books/',views.Book.as_view())

1、Book中没有as_view

2、APIView的as_view

class APIView(View):
    
    @classmethod
    # cls 是 Book类
    def as_view(cls, **initkwargs):
            
        # view = super(APIView, Book).as_view(**initkwargs)
        view = super(APIView, cls).as_view(**initkwargs)
        view.cls = cls
        view.initkwargs = initkwargs

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

3、view = super(APIView, cls).as_view(**initkwargs) ---------------------> View中的as_view

class View(object):
    
    @classonlymethod
    # cls====> Book
    def as_view(cls, **initkwargs):

        def view(request, *args, **kwargs):
            # 实例化产生一个book对象
            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
            # 调dispatch方法
            return self.dispatch(request, *args, **kwargs)
        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

4、return self.dispatch(request, *args, **kwargs) ----------------> dispatch

self====> Book对象，一层层找dispatch

APIView中找到dispatch

class APIView(View):
    
    def dispatch(self, request, *args, **kwargs):

        self.args = args
        self.kwargs = kwargs
        
        # (a)初始化request，就是通过Request类来包装原生request，得到包装后的request
        request = self.initialize_request(request, *args, **kwargs)
        # 从现在开始request就是包装后的request
        self.request = request
        self.headers = self.default_response_headers  # deprecate?

        try:
            # (b) 认证、权限、频率
            self.initial(request, *args, **kwargs)

            # Get the appropriate handler method
            # http_method_names表示列表['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

            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

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

self 是Book对象

class APIView(View):
    # 默认的认证列表类
    authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES
    def initialize_request(self, request, *args, **kwargs):
        """
        Returns the initial request object.
        """
        parser_context = self.get_parser_context(request)
        # (a-b)实例化初始化产生新的request对象
        return Request(
            request,
            parsers=self.get_parsers(),
            authenticators=self.get_authenticators(),  # 认证类实例化产生的对象的列表
            negotiator=self.get_content_negotiator(),
            parser_context=parser_context
        )

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

（a------1）return Request( ··· ) ----------> Request类初始化

    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 ()
        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,)

（b）self.initial(request, *args, **kwargs) -----> 认证、权限、频率

  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
        # （b------1) 认证
        self.perform_authentication(request)
        # （b------2)权限
        self.check_permissions(request)
        # 频率
        self.check_throttles(request)

（b------1) self.perform_authentication(request) -------> 认证

    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

（b------1------1) 调用request的user方法，request是Request实例化产生的对象

class Request(object):
    @property
    def user(self):
        
        # 这里的self是request
        if not hasattr(self, '_user'):
            with wrap_attributeerrors():
                self._authenticate()   # 具体方法如下
        return self._user

（b------1------1-------1) self._authenticate()

class Request(object): 
    def _authenticate(self):
        # 这里的self是request
        # self.authenticators就是在Request实例化的时候，传过来的认证类的对象的列表
        # 即：[auth() for auth in self.authentication_classes]
        for authenticator in self.authenticators:
            try:
                # 重写的就是这个authenticate()方法,
                # 两个参数，第一个是对象本身（自动传）；第二个是这里的self，就是request
                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()