中间件
django 中的中间件(middleware),在django中,中间件其实就是一个类,在请求到来和结束后,django会根据自己的规则在合适的时机执行中间件中相应的方法。
在django项目的settings模块中,有一个 MIDDLEWARE 变量,其中每一个元素就是一个中间件,如下图。
中间件中可以定义四个方法,分别是:
- process_request(self,request) #发送数据
- process_view(self, request, callback, callback_args, callback_kwargs) #views数据
- process_template_response(self,request,response) #只发送render数据
- process_exception(self, request, exception) #异常数据处理
- process_response(self, request, response) #接受数据
以上方法的返回值可以是None和HttpResonse对象,如果是None,则继续按照django定义的规则向下执行,如果是HttpResonse对象,则直接将该对象返回给用户。
自定义中间件
1.创建中间件类(新建文件夹Middle--->m1.py)
1 from django.utils.deprecation import MiddlewareMixin 2 from django.shortcuts import HttpResponse 3 class Row1(MiddlewareMixin): 4 def process_request(self,request): 5 print("111") 6 7 def process_view(self, request, view_func, view_func_args, view_func_kwargs): 8 print("444") 9 10 def process_response(self,request,response): 11 print("999") 12 return response 13 14 class Row2(MiddlewareMixin): 15 def process_request(self,request): 16 print("222") 17 # return HttpResponse("gun") 18 19 def process_view(self, request, view_func, view_func_args, view_func_kwargs): 20 print("555") 21 22 def process_response(self,request,response): 23 print("888") 24 return response 25 26 27 class Row3(MiddlewareMixin): 28 def process_request(self,request): 29 print("333") 30 31 def process_view(self, request, view_func, view_func_args, view_func_kwargs): 32 print("666") 33 34 def process_response(self,request,response): 35 print("777") 36 return response
2.注册中间件settings
1 MIDDLEWARE = [ 2 'django.middleware.security.SecurityMiddleware', 3 'django.contrib.sessions.middleware.SessionMiddleware', 4 'django.middleware.common.CommonMiddleware', 5 'django.middleware.csrf.CsrfViewMiddleware', 6 'django.contrib.auth.middleware.AuthenticationMiddleware', 7 'django.contrib.messages.middleware.MessageMiddleware', 8 'django.middleware.clickjacking.XFrameOptionsMiddleware', 9 "Middle.m1.Row1", 10 "Middle.m1.Row2", 11 "Middle.m1.Row3", 12 ]
3.异常数据处理(主要是views中出现异常)
1 from django.utils.deprecation import MiddlewareMixin 2 from django.shortcuts import HttpResponse 3 class Row1(MiddlewareMixin): 4 def process_request(self,request): 5 print("111") 6 7 def process_view(self, request, view_func, view_func_args, view_func_kwargs): 8 print("444") 9 10 def process_response(self,request,response): 11 print("999") 12 return response 13 14 class Row2(MiddlewareMixin): 15 def process_request(self,request): 16 print("222") 17 # return HttpResponse("gun") 18 19 def process_view(self, request, view_func, view_func_args, view_func_kwargs): 20 print("555") 21 22 def process_response(self,request,response): 23 print("888") 24 return response 25 26 27 class Row3(MiddlewareMixin): 28 def process_request(self,request): 29 print("333") 30 31 def process_view(self, request, view_func, view_func_args, view_func_kwargs): 32 print("666") 33 34 def process_response(self,request,response): 35 print("777") 36 return response 37 38 def process_exception(self, request, exception): 39 if isinstance(exception,ValueError): 40 print("error") 41 return HttpResponse("出现异常。。。。。")
实际效果:
************************************To be continue***********************