Django Learning: Middleware

First, the middleware

1. What is middleware?

Middleware name implies, is interposed between a processing request and response process, relatively lightweight, and changes in the input and output django globally. Because change is global, it is necessary to be cautious and practical, with good will affect the performance.

2, what did?
　　User login
　　logging
　　crsf: for all post requests to do a verification
　　session
　　Rights Management

3、

Note:
　　do batch processing of all requests for time middleware used
　　alone do certain processing functions when used decorator

4, using the steps of:

Step: 
1 ,, to build a folder, which is written a py file 
2, and then start writing class 
1. middleware is a Class A, there are several ways to write 
class M1 (MiddlewareMixin): must inherit 
    def process_request (self, request): request: request everything inside of 
        print ( "m1.request_request") 
        this method which do not easily return value, return value if there is no longer continue to back up, and perform their own process_response top of the response 
        is generally no return value: continue to perform subsequent middleware and view functions 
    DEF process_response (Self, Request, the Response): 
        return the Response 
    
2. mIDDLEWARE in settings plus the path to     
    the folder name .py file name of the class name. 
3. locate inheritance of that class, it took over the class 
  in general do not use the method of introduction, or sometimes there is no update of this class, you put it inherits that class take over,

Graphical analysis process:

process_reques return value:

process_reques None Return Value:

In the middleware settings:

Example:

class MiddlewareMixin(object):
    def __init__(self, get_response=None):
        self.get_response = get_response
        super(MiddlewareMixin, self).__init__()

    def __call__(self, request):
        response = None
        if hasattr(self, 'process_request'):
            response = self.process_request(request)
        if not response:
            response = self.get_response(request)
        if hasattr(self, 'process_response'):
            response = self.process_response(request, response)
        return response

# 至少要有两个类
class Md1(MiddlewareMixin):  #必须继承
    def process_request(self,request):
        print("md1===process_request")
        l = ["/login/"]
        # request.path_info: The current path 
        if request.path_info in l: # Because login is not validated, directly or none on the line 
            return None 
        IF not request.session.get (settings.GDP): 
            return redirect ( "/ login / ") 
        # 
        # If no return value, and continue to follow the middleware view function 
        # If there is a return value, on the implementation of their process_response and above the Response 
    DEF process_response (Self, Request, the Response): 
        Print (" MD1 === process_response1 = ") 
        return the Response # has to return the 

class Md2 (MiddlewareMixin): 
    def process_request(self,request):
        print("md2====process_request2")
    def process_response(self,request,response):
        Print (" MD2 ==== process_response2 ") 
        return the Response

test:

def testMD(request):
    print("view.test")
    return HttpResponse("...")

Return result:

Django Learning: Middleware

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