I'm trying to check if the user has safe data, but if they don't, they will be redirected to /waitlist.

[bznbot]

`Why it is not working?

`export async function POST(req: NextRequest, res: NextResponse) {
try {
const json = await req.json();
const body = userJoinSchema.parse(json);

const userSafeData = verifyTelegramWebAppData(body.initData);

if (!userSafeData) {
  return NextResponse.redirect(new URL("/waitlist", req.url));
}

const user = parseInitData(body.initData);

return NextResponse.json(user);

} catch (error) {
return NextResponse.json({ error: error }, { status: 500 });
}
}``

[icyJoseph]

Hi,

First a minor thing, but the Route Handlers, such as GET, POST, etc, do not receive a second response argument. Please change it to this:

import { type NextRequest, NextResponse } from 'next/server';

export async function POST(req: NextRequest) {

Now onto the actual issue. This one can catch people of all levels of experience, off guard.

1. You make a fetch request with method POST
2. Your endpoint receives that, and redirects this request, if !userSafeData is present
3. The browser receives this response, and sees it is a redirect, so it follows it, and gets a response for that
4. now your fetch request at 1 resolves, and you get the result collected at 3

That is to say that the document doesn't navigate, because the document didn't start the request, rather, it was the JavaScript fetch context, that did it.

Of course, one could return a 200 in step 2, with a nextURL, and redirect users there, but that's also not very ideal... because now people who, outside of the browser context, reach for your POST endpoint, won't be redirect automatically to the waitlist.

One way to do this with a form tag, and with method POST, and action equal to the endpoint that does the check. Then since it is a form submission, the document will navigate.

Alternatively, a React Server Action, can also get you a somewhat similar experience.

I've coded some, bad, but functional examples here: https://stackblitz.com/edit/nextjs-eusbca?file=app%2Fpage.tsx

Maybe this post is also helpful to read: https://blog.jim-nielsen.com/2021/fetch-and-3xx-redirect-status-codes/