TanStack Start: how to return a response from a server middleware?

[mccuna]

Hi, I've been trying to build an authentication middleware for my TanStack Start app but I could not find out how to create how to halt the execution and return a response to the client if the user is not logged-in.

I've tried something like

export const authMiddleware = createMiddleware().server(async (ctx) => {
	const request = getWebRequest();
	invariant(request, 'Request not found');
	const { session, user } = (await auth.api.getSession(request)) ?? {
		session: null,
		user: null,
	};

	if (!session) {
		await sendWebResponse(new Response('Unauthenticated', { status: 401 }));
		return; // <--- results in typescript complaining about the return type
	}

	return ctx.next({
		sendContext: {
			session,
			user,
		},
	});
});

But Typescript complains about the return type:

│ │ │ Type 'undefined' is not assignable to type 'ServerResultWithContext<unknown, undefined, undefined, { session: { id: string; createdAt: Date; updatedAt: Date; userId: string; expiresAt: Date; token: string; ipAddress?: string | null | undefined; userAgent?: string | ... 1 more ... | undefined; impersonatedBy?: string | ... 1 more ... | undefined; }; user: { .....'. ts (2345) [51, 57]

What is the right way of returning a response directly and to prevent other middlewares and the server function from executing?

[schiller-manuel]

you would need to throw a redirect or an Error

[rburgst]

when I throw an error and setResponseStatus(401) I still get a 500