when the localePrefix is set to as-needed and when the root is /

[Maofree]

Description

Hi
I take as an example a site with two languages, the default is Italian and English is the secondary
for Italian I do not want /it to appear in the urls, while for the English ones it does

export const routing = defineRouting({
locales: ['it', 'en'],
defaultLocale: 'it',
localePrefix: 'as-needed'
});

further down I also report how I solved this problem. The case where the iso code is not used for the default language urls is a very frequent behavior

Verifications

• I've verified that the problem I'm experiencing isn't covered in the docs.
• I've searched for similar, existing issues on GitHub and Stack Overflow.
• I've compared my app to a working example to look for differences.

Mandatory reproduction URL

App Router

Reproduction description

I have seen that with this configuration, loading the homepage with
http://localhost:3000/
does not create the cookie
NEXT_LOCALE with the value "it"
instead if I used
http://localhost:3000/it
it does
and also with
http://localhost:3000/en
it creates the cookie NEXT_LOCALE with the value "en"

go from
http://localhost:3000/en
to
http://localhost:3000/it

it changes the value of the cookie from en to it, correctly, in fact
http://localhost:3000/it
becomes
http://localhost:3000/

the problem comes when I go from
http://localhost:3000/en
to
http://localhost:3000/

in this case the cookie value does not become it and therefore the page returns to
http://localhost:3000/en

Expected behaviour

the problem is that the cookie is not created when the language iso code is not present in the url

the problem is solved by creating the cookie also with this url
http://localhost:3000/
which is the case managed with the option
localePrefix: 'as-needed'

I solved it this way into middleware.ts

`import createMiddleware from 'next-intl/middleware';
import { NextResponse, type NextRequest } from 'next/server';
import { routing } from './i18n/routing';

const nextIntlMiddleware = createMiddleware(routing);

export default function middleware(request: NextRequest) {
const pathname = request.nextUrl.pathname;
const localeCookie = request.cookies.get('NEXT_LOCALE');

// Only for the root (/)
if (pathname === '/' && localeCookie?.value !== routing.defaultLocale) {
const response = NextResponse.next();

// Always overwrite the cookie with the default language
response.cookies.set('NEXT_LOCALE', routing.defaultLocale, {
  path: '/',
  sameSite: 'lax',
});

return response;

}

return nextIntlMiddleware(request);
}

export const config = {
matcher: [
'/((?!api|trpc|_next|_vercel|.\..).*)'
]
};`

this way when you return to the homepage / the cookie value is always set to the same as the default one

bye

[amannn]

Usage questions should go in the discussions please.

The behavior of handling prefixes with as-needed and cookies is documented in the corresponding docs.