Middleware trong Django là gì và để làm gì?

Middleware là callable bọc quanh pipeline request → view → response, chạy trước/sau view cho mọi request.

Hợp với các cross-cutting concern: auth, session, CSRF, logging, GZip, security header, gắn tenant context vào request.

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

    def __call__(self, request):
        request.id = uuid.uuid4().hex
        response = self.get_response(request)
        response['X-Request-ID'] = request.id
        return response

Register vào MIDDLEWARE setting; thứ tự khai báo rất quan trọng — xem [[#9224]].

• Đừng nhồi business logic vào middleware vì nó chạy cho mọi request kể cả static/admin, rất dễ thành bottleneck.
• Việc nào chỉ liên quan một view thì đặt ở view hoặc decorator.

Middleware is a callable that wraps the request → view → response pipeline, running before/after the view for every request.

It fits cross-cutting concerns: auth, session, CSRF, logging, GZip, security headers, tenant context.

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

    def __call__(self, request):
        request.id = uuid.uuid4().hex
        response = self.get_response(request)
        response['X-Request-ID'] = request.id
        return response

Register it in the MIDDLEWARE setting (order matters — see [[#9224]]).

Pitfall: Do not stuff business logic into middleware. It runs on every request, including static/admin — easy to become a bottleneck. Anything view-specific belongs in the view or a decorator.