Django rest framework源码分析（2）----权限

添加权限

（1）API/utils文件夹下新建premission.py文件，代码如下：

• message是当没有权限时，提示的信息

# utils/permission.py


class SVIPPremission(object):
    message = "必须是SVIP才能访问"
    def has_permission(self,request,view):
        if request.user.user_type != 3:
            return False
        return True


class MyPremission(object):
    def has_permission(self,request,view):
        if request.user.user_type == 3:
            return False
        return True

（2）settings.py全局配置权限

#全局
REST_FRAMEWORK = {
    "DEFAULT_AUTHENTICATION_CLASSES":['API.utils.auth.Authentication',],
    "DEFAULT_PERMISSION_CLASSES":['API.utils.permission.SVIPPremission'],
}

（3）views.py添加权限

• 默认所有的业务都需要SVIP权限才能访问
• OrderView类里面没写表示使用全局配置的SVIPPremission
• UserInfoView类，因为是普通用户和VIP用户可以访问，不使用全局的，要想局部使用的话，里面就写上自己的权限类
• permission_classes = [MyPremission,]   #局部使用权限方法

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 BaseAuthentication
from API.utils.permission import SVIPPremission,MyPremission

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
    permission_classes = []          #不里面为空，代表不需要权限
    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(只有SVIP用户才能看)
    '''

    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)


class UserInfoView(APIView):
    '''
       订单相关业务(普通用户和VIP用户可以看)
       '''
    permission_classes = [MyPremission,]    #不用全局的权限配置的话，这里就要写自己的局部权限
    def get(self,request,*args,**kwargs):

        print(request.user)
        return HttpResponse('用户信息')

from django.contrib import admin
from django.urls import path
from API.views import AuthView,OrderView,UserInfoView

urlpatterns = [
    path('admin/', admin.site.urls),
    path('api/v1/auth/',AuthView.as_view()),
    path('api/v1/order/',OrderView.as_view()),
    path('api/v1/info/',UserInfoView.as_view()),
]

# 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）测试

普通用户访问OrderView,提示没有权限

 

 普通用户访问UserInfoView，可以返回信息

 

 权限源码流程

 （1）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
        #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

（2）initial

    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
        #4.实现认证
        self.perform_authentication(request)
        #5.权限判断
        self.check_permissions(request)
        self.check_throttles(request)

（3）check_permissions

里面有个has_permission这个就是我们自己写的权限判断

    def check_permissions(self, request):
        """
        Check if the request should be permitted.
        Raises an appropriate exception if the request is not permitted.
        """
        #[权限类的对象列表]
        for permission in self.get_permissions():
            if not permission.has_permission(request, self):
                self.permission_denied(
                    request, message=getattr(permission, 'message', None)
                )

（4）get_permissions

 def get_permissions(self):
        """
        Instantiates and returns the list of permissions that this view requires.
        """
        return [permission() for permission in self.permission_classes]

（5）permission_classes

 

 所以settings全局配置就如下

#全局
REST_FRAMEWORK = {
   "DEFAULT_PERMISSION_CLASSES":['API.utils.permission.SVIPPremission'],
}

 

内置权限

 django-rest-framework内置权限BasePermission

默认是没有限制权限

class BasePermission(object):
    """
    A base class from which all permission classes should inherit.
    """

    def has_permission(self, request, view):
        """
        Return `True` if permission is granted, `False` otherwise.
        """
        return True

    def has_object_permission(self, request, view, obj):
        """
        Return `True` if permission is granted, `False` otherwise.
        """
        return True

 

我们自己写的权限类，应该去继承BasePermission,修改之前写的permission.py文件

# utils/permission.py

from rest_framework.permissions import BasePermission

class SVIPPremission(BasePermission):
    message = "必须是SVIP才能访问"
    def has_permission(self,request,view):
        if request.user.user_type != 3:
            return False
        return True


class MyPremission(BasePermission):
    def has_permission(self,request,view):
        if request.user.user_type == 3:
            return False
        return True

 

总结：

（1）使用

• 自己写的权限类：1.必须继承BasePermission类；  2.必须实现：has_permission方法

（2）返回值

• True   有权访问
• False  无权访问

（3）局部

• permission_classes = [MyPremission,] 

 （4）全局

REST_FRAMEWORK = {
   #权限
    "DEFAULT_PERMISSION_CLASSES":['API.utils.permission.SVIPPremission'],
}