Abin middleware ya aiki a cikin FastAPI?

Question

Accepted Answer

**Middleware** a cikin FastAPI shine code wanda ya gudu ga **kowane bugi da amsewa** — rufe a cikin abubuwa-ka na gida wajen tunani bugi-bugi akasari masu alaƙa da ruwan zafi, lokaci, CORS, da kara headers. FastAPI yana amfani da tsarin middleware na Starlette (ya ginawa ne akan ASGI).

## Rubutu custom middleware

```python
import time

@app.middleware("http")
async def add_timing(request: Request, call_next):
    start = time.time()
    response = await call_next(request)        # call the endpoint (and any inner middleware)
    response.headers["X-Process-Time"] = str(time.time() - start)   # modify the response
    return response
```

Alkawari: code kafin `await call_next(request)` yana gudu a hanyar **ciki** (kafin aikin hannu), `call_next` ya buga aikin hannu, kuma code bayan haka ya gudu a hanyar **waje** (canja amsewa). Wannan ya rufe kowane bugi — anan, ƙara header lokaci zuwa duk amsewa.

## Bugin/amsewon samuwa

```text
Request  → MW1 → MW2 → endpoint
Response ← MW1 ← MW2 ← endpoint
Middleware wraps the endpoint; runs in order on the way in, reverse on the way out.
```

## Middleware da aka shiga / sannu

```python
from fastapi.middleware.cors import CORSMiddleware
from fastapi.middleware.gzip import GZipMiddleware

app.add_middleware(CORSMiddleware, allow_origins=["https://app.example.com"], ...)  # CORS
app.add_middleware(GZipMiddleware, minimum_size=1000)                               # compression
```

Middleware an saba a ƙara shi ta hanyar `add_middleware` — CORS (ba da izini ga bugi na gida-gida), GZip (damje amsewa), da nasarar mai aminci-ganima su ne sannu da aka saka.

## Sannu na amfani da middleware

```text
✓ Logging / request timing / metrics
✓ CORS (cross-origin request handling)
✓ Adding security or custom headers
✓ Response compression (GZip)
✓ Request ID / correlation ID injection
```

## Middleware vs dogaro

```text
Middleware   → runs for ALL requests; works at the raw request/response level (headers,
               timing, the whole response). Best for truly global concerns.
Dependencies → per-endpoint (or grouped) logic with access to parsed params, DI, and
               typed values. Best for auth, validation, shared parameters.
→ Use middleware for global cross-cutting concerns; dependencies for endpoint logic.
```

## Me ya sa ya zama mahimmanci

Middleware shi ne daidai aikin don **gida, bugi-bugin lafiya** a cikin FastAPI — ilimi wanda yakamata ya aiki ga kowane bugi da amsewa, kamar ruwan zafi, lokaci bugi, CORS, damje, da riga-rigima.

Sanin sa mahimmaci ne don tsara aikace-aikacen daidai: middleware ya rufe duk abubuwa (yana gudu kafin da bayan, tare da ikon canja bugi da amsewa duka), wanda ya sa shi zai dace da halayye na aikace-aikace wanda zai zama mai wahala da kuskure-kusure a maimaita a kowane gida.

Sanin ya kasance bambance tsakanin **middleware** (gida, matakin bugi/amsewa) da **dogaro** (kowannen-gida, tare da izinin ƙarasa/nau'i da DI — mafi kyau na aminci da tabbatar) muhimmi ne na zaɓin kayan gida daidai.

Buttu sannu kamar CORS da damje ana sakawa su ta middleware da aka shiga, yayin da middleware na zabe ya rufe ruwan zafi da aiki — wanda ya sa ilimin yada-yada da fa'ida-fa'ida, sannu-sannu ne don gina APIs mabur-mabur da lura.