Just checking, are you doing the fetch in a client component (not server)

This is the full code:

The expected methood is when someone come to the site then check if he have token in the cookies and if yes then validate that, and if the validation is success then set the userData into a cookie, but the first step for me to call the api succesfully like in other files

Ahh and good to know that im using JS not typescript

Sorry, i cannot get what the problem is, i cannot fetch in dev mode and also tried to pass the localhost:3000 prefix for the fetch url but this doesnt works well either

I show the other code where it works correctly

The API:
import { NextResponse } from "next/server";
import { cookies } from "next/headers";

export async function POST(request) {
const body = await request.json();

cookies().set("selectedLanguage", body?.selectedLanguage || "hu");

return NextResponse.json({
success: true,
data: { language: body?.selectedLanguage },
});
}


the code where i fetch this (inside a context):

const setSelectedLanguageCookie = (selectedLanguage) => {
fetch("/api/settings/language", {
method: "POST",
headers: {
"Content-Type": "application/json",
},
body: JSON.stringify({ selectedLanguage }),
})
.then((response) => response.json())
.then()
.catch((error) => console.error(error));
};

Did you read the link?

You mean that i should create a file like fetch.js and inside that have the fetch methood and in files like page.js just call that fetch.js file?

Yes

Just do the code that you would do on the API, but on the server (so yeah, you can create a file that has the code)

Okay so if i create a file like saveTheUserData.js and inside that just have a function which ones runs the
fetch(‘api/user’ ….) then call this function inside the page.js this should work fine right?

Yeah, and if you still want the API, you can call that file also

Alright i give it a try now thanks

tried something like this:
lib/saveUserData.js :
export default function saveUserData(data) {
fetch("/api/user", {
method: "POST",
headers: {
"Content-Type": "application/json",
},
body: JSON.stringify({ hello: data }),
})
.then((response) => response.json())
.then((data) => {
return data;
})
.catch((error) => console.error(error));
}
and now inside the page.js file:

export default function Page() {
const token = cookies().get("token");

const data = saveUserData("Hello");
console.log(data);
if (token) {
redirect("/dashboard");
} else {
redirect("/login/sign-in");
}
}

and the same erroor (INVALID_URL)

any suggestions?