Trying to achieve the same type of thing you would in Expressjs with middleware then setting like req.user = user

This is basically the Express equivalent of what I want to do:

app.use((req, res, next) => {
    const token = req.cookies.token;
    const user = /* Code to fetch user from DB */;

    req.user = user;
    next();
});

Using NextJS 14 with the app router btw ^^

heya you can use a custom header for that

// @file middleware.ts
export default async function middleware(
  req: NextRequest
): Promise<NextResponse> {
  // do some stuff
  const username = "...";

  // suppose i want to pass username to the pages
  const headers = new Headers(req.headers);
  headers.append("X-Middleware-Username", username);
  return NextResponse.next({ request: { headers } });
}

// @file /app/page.tsx
export default function Page() {
  const username = headers().get("X-Middleware-Username")!;
  return <p>Welcome aboard, {username}!</p>
}

the header name can be whatever you wanted, it's standard to use X-... for "internal" headers. for me i'd use a different file to store it to make it "dry-er"

// @file utils/headers.ts
export const MIDDLEWARE_USERNAME_HEADER = "X-Middleware-Username";

I want to do it from backend -> backend

will that still work

yeah it should work

The custom header is the only way I've found to do it, because the middleware and the backend are separate processes.