20 Django组件之中间件

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yuan先生博客

中间件语法

自定义中间件，继承于MiddlewareMixin

from django.utils.deprecation import MiddlewareMixin
class CustomerMiddleware(MiddlewareMixin):
    def process_request(self,request):
        print(request.get_host())
        print("CustomerMiddleware process_request.....")

在setting的MIDDLEWARE中注册新的中间件

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'app.my_middleware.CustomerMiddleware'
]

定义有request和response的中间件。request不用反回执，response一定要有返回值。request有返回HTTPResponse后将会话进行拦截，直接交给自己的response返回给浏览器。

请求执行request中方法，返回时执行response中的方法

class CustomerMiddleware2(MiddlewareMixin):
    def process_request(self,request):
        print(request.get_host())
        print("CustomerMiddleware process_request.....")
    def process_response(self,request,response):
        print("CustomerMiddleware2 response.....")
        #response必须有返回值
        return response

process_view()

class CustomerMiddleware3(MiddlewareMixin):
    def process_request(self,request):
        print(request.get_host())
        print("CustomerMiddleware process_request.....")
    def process_response(self,request,response):
        print("CustomerMiddleware2 response.....")
        #response必须有返回值
        return response
    def process_view(self,request,callback,callback_args,callback_kwargs):
        #这里callback就是对应视图函数
        #这里不要返回HTTPResponse，返回就不会朝下继续执行，直接返回向上执行response
        print("CustomerMiddleware3 view")

process_exception()

在代码正常执行的情况下不会被执行，只要查找到一个HTTPResponse对象，即返回

class CustomerMiddleware3(MiddlewareMixin):
    def process_request(self,request):
        print(request.get_host())
        print("CustomerMiddleware process_request.....")
    def process_response(self,request,response):
        print("CustomerMiddleware2 response.....")
        #response必须有返回值
        return response
    def process_view(self,request,callback,callback_args,callback_kwargs):
        #这里callback就是对应视图函数
        #这里不要返回HTTPResponse，返回就不会朝下继续执行，直接返回向上执行response
        print("CustomerMiddleware3 view")
    def process_exception(self,request,response,exception):
        #exception为视图函数中的错误信息
        #返回错误的HTTPResponse对象，有一个exception返回即返回，不会一级一级返回
        pass

中间件应用案例

1. 做ip访问频率限制
2. 访问视图检测是不是有session验证，有则放行，没有则返回login页面，避免多个视图添加login装饰器

大量需要验证，则通过中间件实现验证，相反则通过添加装饰器来完成

from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import redirect
from userauth import settings
class AuthMiddleware(MiddlewareMixin):
    def process_request(self,request):
        white_list=settings.WHITE_LIST
        if request.path in white_list:
            return None#访问白名单路由直接返回None
        if not request.user.is_authenticated:
            #没有通过认证则调转到主页
            return redirect('/login/')