Me za ake Next.js middleware?

Question

Accepted Answer

**Middleware** shine code da ke aiki **kafin abin ba za a gama** — akan Edge, kafin shafin ko route handler ya haura. Yana ba ka ikon bincika da sake rubuta/sake tofa bukatun, saita headers, ko bincika auth don jiya hanyoyi a wuri guda.

## Bayyana middleware

```ts
// middleware.ts (at the project root)
import { NextRequest, NextResponse } from "next/server";

export function middleware(req: NextRequest) {
  const token = req.cookies.get("session")?.value;

// protect /dashboard — redirect unauthenticated users to login
  if (req.nextUrl.pathname.startsWith("/dashboard") && !token) {
    return NextResponse.redirect(new URL("/login", req.url));
  }
  return NextResponse.next(); // allow the request to proceed
}

// only run on these paths (performance — don't run on every asset)
export const config = { matcher: ["/dashboard/:path*", "/account/:path*"] };
```

## Abin da middleware zai iya yi

```ts
NextResponse.redirect(url);          // send the user elsewhere (auth gates)
NextResponse.rewrite(url);           // serve different content, URL unchanged (A/B, i18n)
NextResponse.next();                  // continue, optionally with modified headers
// req.geo / req.cookies / req.headers — inspect location, auth, etc.
```

Hanyoyin amfani: **authentication gating**, **redirects** (tushe na locale/geo, www→apex), **A/B testing** ta hanyar rewrites, saita **security headers**, da bot/feature flags.

## Manyan iyakoki

```text
⚠️ Runs on the EDGE runtime → no Node.js APIs (no fs, limited libraries)
⚠️ Must be FAST — it runs before every matched request; heavy work adds latency
⚠️ Can't access the database directly for complex auth — do lightweight checks
   (e.g. verify a JWT/cookie exists); do full auth in the page/handler
```

Config `matcher` mahimmanci: damje middleware zuwa kawai hanyoyi da suke bukatar shi, don ya kada yi aiki akan jigon taiyo da ya rasa gurin.

## Me ya sa ake makili

Middleware shine gida gida na tunani don logic da ke gida — tunavon authentication, alhali hanya, rewrites, da headers — ana aiki a jiya hanyoyi ba tare da maimaita code a kowane shafi ba.

Sanin iyakokin Edge sa (sauri, babu Node APIs, bincike mai fadi kawai) da saita `matcher` shine abin da ya ba ka damar amfani dashi daidai para watsy-watsy da hanyoyi.