Environmental Science

Win10
Python3.6.6
Django2.1.3

Middleware role

• Middleware is used to globally modify the input or output of Django.

Common uses of Middleware

• cache
• Session authentication
• Log record
• abnormal

Middleware execution process

image

Global exception capture implementation

Create django project & add app

django-admin startproject middleware
cd middleware
django-admin startapp app

Add app to project

# middleware/settings.py
# Installed? Applast add app
INSTALLED_APPS = [
    'app',
]

Edit middleware and add to project

• Note: middleware registration access has certain relevance, and the location cannot be placed at will

# Create app/middleware.py and edit
from django.http import JsonResponse


class CustomMiddleware:
    def __init__(self, get_response):
        print("Execute on program start, Only once")
        self.get_response = get_response

    def __call__(self, request):
        print("Middleware start")
        response = self.get_response(request)
        print("End of Middleware")
        return response

    def process_view(self, request, view_func, view_args, view_kwargs):
        print("Execute before requesting actual function")

    def process_exception(self, request, exception):
        print("Execute when the program is abnormal")
        return JsonResponse({"msg": exception.args[0], "code": -1})


//Edit middleware.settings.py
MIDDLEWARE = [
    ...
    'app.middleware.CustomMiddleware'
]

Write an exception

# app/views.py
from django.http import JsonResponse


def json_response(request):
    print('json_response')
    err = 3 / 0
    return JsonResponse({"msg": "ok", "code": 0})

Add to route

# middleware/urls.py

from app.views import json_response, view_response

urlpatterns = [
    ...
    path("view", view_response)
]

1. Operation test
   • Visit: http://127.0.0.1:8000/json/

   • Result

     
     
     

     image

Another sleep use log

# Add in the middleware function process view
print("path: {}; method: {}; data: {}".format(request.get_full_path(), request.method, request.body or ''))

Reference resources:

• https://docs.djangoproject.com/zh-hans/2.1/topics/http/middleware/