django--Middleware

1. Principle

In Django, the middleware is actually a class, and after the request arrives and ends, Django executes the appropriate method in the middleware at the right time according to its own rules.

When the request arrives, there is a layer of middleware in the middle of the WSGI and URLs, exactly the 4-tier approach and the Django Framework's handling:

1. Process_request (Self,request)

2. Process_view (self, request, callback, Callback_args, Callback_kwargs)

3. Views

4. process_exception (Self, request, exception)

5. Process_response (self, request, response)

The names and parameters of these functions cannot be changed, and any link with response will be handed to Process_response () to be processed and returned to the user.

2. Custom MiddlewareCreate a Package

middle1.py

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class mmm(object):    def process_request(self,request):        print "mmm.process_request"    def process_view(self,request,callback,callback_args,callback_kwargs):        print "mmm.process_view"    def process_response(self,request,response):        print "mmm.process_response"        return responseclass xxx(object):    def process_request(self,request):        print "xxx.process_request"    def process_view(self,request,callback,callback_args,callback_kwargs):        print "xxx.process_view"    def process_response(self,request,response):        print "xxx.process_response"        returnresponse

settings.py

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MIDDLEWARE_CLASSES = [    ‘django.middleware.security.SecurityMiddleware‘,    ‘django.contrib.sessions.middleware.SessionMiddleware‘,    ‘django.middleware.common.CommonMiddleware‘,    # ‘django.middleware.csrf.CsrfViewMiddleware‘,    ‘django.contrib.auth.middleware.AuthenticationMiddleware‘,    ‘django.contrib.auth.middleware.SessionAuthenticationMiddleware‘,    ‘django.contrib.messages.middleware.MessageMiddleware‘,    ‘django.middleware.clickjacking.XFrameOptionsMiddleware‘,    ‘middleware.middle1.mmm‘,    ‘middleware.middle1.xxx‘,]

views.py

123	defindex(request):    print "view"    returnHttpResponse("index")

Ide

You can see the order of execution, noting that the order of execution of Process_response () is from backward forward.

3. Source code

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#Django自动去settings里找 MIDDLEWARE_CLASSES process_request_list=[]process_view_list=[]process_response_list=[]process_exception_list=[]for class inMIDDLEWARE_CLASSES:    obj = class()    if hasattr(obj,process_request):        process_request_list.append(obj.process_request)    if hasattr(obj,process_view):        process_view_list.append(obj.process_view)    if hasattr(obj,process_response):        process_response_list.append(obj.process_response)    if hasattr(obj,process_exception):        process_exception_list.append(obj.process_exception)for i in process_request_list:    i()for i in process_view_list:    i()#Django渲染for i in process_exception_list:    i()for i in process_response_list:    i()

4.process_exceptionviews.py

12	defindex(request):    raiseException("报错了")

middleware/middle.py

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class mmm(object):    def process_request(self,request):        print "mmm.process_request"    def process_view(self,request,callback,callback_args,callback_kwargs):        print "mmm.process_view"    def process_response(self,request,response):        print "mmm.process_response"        returnresponse    def process_exception(self, request, exception):        print exception        return request

Browser

IDE

Attention:?

• The Process_request and Process_view methods are executed in the order of the custom middleware
  

• Process_exception and Process_response are executed in the order of the middleware from the back forward
  

From for notes (Wiz)

django--Middleware