Why middleware matters in Django

Introduction

Middleware helps Django handle tasks before and after a web request. It makes your app smarter and easier to manage.

You want to check if a user is logged in before showing a page.

You need to add special headers to every response from your site.

You want to log details about each visitor automatically.

You want to block bad users or bots from accessing your site.

You want to modify requests or responses without changing your main code.

Syntax

Django

class MyMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        # Code before view runs
        response = self.get_response(request)
        # Code after view runs
        return response

The __init__ method runs once when the server starts.

The __call__ method runs for each request, letting you add code before and after the view.

Examples

This middleware prints messages before and after the view runs.

Django

class SimpleMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        print('Before view')
        response = self.get_response(request)
        print('After view')
        return response

This middleware adds a custom header to every response.

Django

class AddHeaderMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        response = self.get_response(request)
        response['X-Custom-Header'] = 'Hello'
        return response

Sample Program

This middleware logs the URL path of each request and the status code of the response.

Django

class LogMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        print(f'Received request: {request.path}')
        response = self.get_response(request)
        print(f'Sent response with status: {response.status_code}')
        return response

Important Notes

Middleware runs in the order listed in settings.MIDDLEWARE.

Middleware can change requests and responses, so use it carefully.

Always return the response object from your middleware.

Summary

Middleware lets you add code before and after views run.

It helps with tasks like logging, security, and modifying responses.

Middleware makes your Django app easier to manage and extend.