Unit 8 Middleware

One. Middleware

What is it
Middleware in Django is a lightweight, low-level plug-in system that can intervene in Django's request and response processing and globally modify Django's input or output.
What to do
If you want to modify the request, such as the HttpRequest object passed to the view.Or you want to modify the HttpResponse object returned by the view, which can be achieved through middleware.
Where:

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',]

2. Principle and application of middleware

The principle of middleware

Common hook methods

process_request(self,request) # This method will be executed before django processes the requestprocess_response(self, request, response) # After django returns the response, execute this method

Define and call
Create define middleware location

Custom Middleware

The first def
calls this middleware before processing the request
The second def
returns the middleware after the view returns the response

3. Registration and use of middleware

Registration of middleware

Middleware effect
Normal effect

Incorrect effect