Custom Django Middleware with Request/Response Processing Pipeline

Snippet

Custom Django Middleware with Request/Response Processing Pipeline

Django middleware sits between the web server and your view, processing every request and response. This expert-level middleware implements rate limiting using an in-memory counter, tracks request counts per IP address, blocks excessive requests with HTTP 429, and injects custom headers into responses. The __init__ receives the get_response callable, __call__ processes each request/response pair, and process_exception handles unexpected errors globally.

snippet.py
python
from django.http import JsonResponse
from django.utils.deprecation import MiddlewareMixin
 
class RateLimitMiddleware(MiddlewareMixin):
    def __init__(self, get_response):
        self.get_response = get_response
        self.request_counts = {}
 
    def __call__(self, request):
        client_ip = request.META.get('REMOTE_ADDR')
        self.request_counts[client_ip] = self.request_counts.get(client_ip, 0) + 1
 
        if self.request_counts[client_ip] > 100:
            return JsonResponse({'error': 'Rate limit exceeded'}, status=429)
 
        response = self.get_response(request)
        response['X-Request-Count'] = self.request_counts[client_ip]
        return response
 
    def process_exception(self, request, exception):
        return JsonResponse({'error': str(exception)}, status=500)

django

Breakdown

from django.utils.deprecation import MiddlewareMixin

Imports MiddlewareMixin for compatibility with Django's middleware framework

def __init__(self, get_response):

Initializer receives the next middleware/view in the chain as get_response

self.request_counts = {}

In-memory dictionary storing request counts per client IP

client_ip = request.META.get('REMOTE_ADDR')

Extracts client IP from request metadata for rate tracking

if self.request_counts[client_ip] > 100:

Checks if client has exceeded the rate limit threshold

return JsonResponse({'error': 'Rate limit exceeded'}, status=429)

Returns 429 Too Many Requests when limit is exceeded

response['X-Request-Count'] = self.request_counts[client_ip]

Injects custom header with current request count into response

def process_exception(self, request, exception):

Override to catch and transform unhandled exceptions globally

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Custom Django Middleware with Request/Response Processing Pipeline

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