Middleware katika Django ni nini?

Question

Accepted Answer

**Middleware** ni framework ya hooks zinazochakata **kila request na response** kwa ujumla, zikiwa kati ya web server na views zako. Kila middleware inaweza kukagua/kubadilisha requests zinapoingia na responses zinapotoka — bora kwa masuala ya cross-cutting kama authentication, security headers, sessions, na logging.

## Mtiririko wa request/response kupitia middleware

```text
Request  → MW1 → MW2 → MW3 → VIEW
Response ← MW1 ← MW2 ← MW3 ← VIEW

Middleware wraps the view like layers of an onion:
  - on the way IN (request): top-to-bottom
  - on the way OUT (response): bottom-to-top (reverse order)
```

## Middleware iliyojengwa ndani ya Django (katika settings.py)

```python
MIDDLEWARE = [
    "django.middleware.security.SecurityMiddleware",          # security headers (HSTS, etc.)
    "django.contrib.sessions.middleware.SessionMiddleware",   # enables request.session
    "django.middleware.common.CommonMiddleware",
    "django.middleware.csrf.CsrfViewMiddleware",              # CSRF protection
    "django.contrib.auth.middleware.AuthenticationMiddleware",# enables request.user
    "django.middleware.clickjacking.XFrameOptionsMiddleware", # clickjacking protection
]
# ORDER MATTERS — e.g. SessionMiddleware must come before AuthenticationMiddleware
```

Sehemu kubwa ya utendaji wa msingi wa Django ni middleware: sessions (`request.session`), authentication (`request.user`), ulinzi wa CSRF, na security headers zote zinatoka kwa middleware iliyojengwa ndani. **Mpangilio ni muhimu** — middleware fulani inategemea nyingine kuendesha kwanza.

## Kuandika custom middleware

```python
class TimingMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response          # the next middleware/view

def __call__(self, request):
        # --- code here runs on the way IN (before the view) ---
        import time; start = time.time()

response = self.get_response(request)     # call the next layer (eventually the view)

# --- code here runs on the way OUT (after the view) ---
        response["X-Response-Time"] = f"{time.time() - start:.3f}s"
        return response
```

Middleware ni callable: code kabla ya `self.get_response(request)` inaendesha kwenye request, code baada yake inaendesha kwenye response. Hii inakuruhusu kutenda kabla na baada ya utekelezaji wa view.

## Matumizi ya kawaida ya middleware

```text
✓ Authentication / setting request.user
✓ Security headers (CSP, HSTS, X-Frame-Options)
✓ Request/response logging, timing, metrics
✓ Sessions, locale/i18n detection, CORS
✓ Rate limiting, maintenance mode, custom request preprocessing
```

## Middleware dhidi ya views/decorators

```text
Middleware → GLOBAL, cross-cutting concerns affecting EVERY (or most) request
Decorators/view logic → per-view concerns specific to certain endpoints
→ Use middleware for app-wide behavior; decorators for selective behavior.
```

## Kwa nini ni muhimu

Middleware ni ya msingi kwa jinsi Django inavyochakata requests — kuielewa kunaeleza jinsi sehemu kubwa ya utendaji wa msingi wa framework inavyofanya kazi kwa kweli na kunatoa mfumo sahihi kwa **masuala ya kimataifa, ya cross-cutting**.

Kutambua kwamba sessions, authentication (`request.user`), ulinzi wa CSRF, na security headers zote zinatoka kwa middleware iliyojengwa ndani kunaondoa siri ya ushughulikiaji wa request wa Django na kunaonyesha kwa nini vipengele hivi "vinafanya kazi tu." Kuelewa **mtiririko wa request/response wa tabaka la kitunguu** (middleware ikifunika view, ikichakata requests kutoka juu hadi chini na responses kutoka chini hadi juu) na kwamba **mpangilio ni muhimu** (middleware fulani inategemea nyingine, kama authentication inayohitaji sessions kwanza) ni muhimu kwa kusanidi Django kwa usahihi na kutatua matatizo.

Uwezo wa **kuandika custom middleware** ni wa thamani kwa kutekeleza tabia ya programu nzima kwa usafi — logging, timing, custom headers, rate limiting, maintenance mode — mahali pamoja badala ya kuirudia katika views.

Kujua wakati wa kutumia middleware (masuala ya kimataifa yanayoathiri requests nyingi) dhidi ya decorators au mantiki ya view (masuala ya kila endpoint) ni uamuzi muhimu wa kiusanifu.

Middleware ndipo Django inashughulikia uchakataji wa request/response unaohusu programu nzima, kuifanya kuwa maarifa muhimu na yanayohusika kivitendo kwa kuelewa sehemu za ndani za framework na kujenga programu zilizopangwa vizuri zenye utenganisho sahihi wa masuala ya cross-cutting.