Register rest field authentication with REST API

Question

I'm trying to add some user meta information to the existing wp/v2/users REST endpoint. However, it looks like additional authentication is required, i.e. I get this (output in comments):

    error_log( is_user_logged_in() ); // true
    register_rest_field( 'user',
        'is_logged_in',
        array(
            'get_callback' => function () {
                return is_user_logged_in(); // false
            },
        )
    );

(so it doesn't seem possible to get actual user meta in the new field I registered).

Firstly: please correct me if I'm wrong on this point because it would make things much easier.

However, assuming additional authentication is required: I tried just setting _wpnonce to the nonce I got when logged in, and got back a 403. I simply want to be able to send any user who is logged in their own user data in JSON format. What is the correct way to do this?

Answer 1

It is a bad API design to return different structure based on "external data" not passed in the request itself.

Either construct different API for logged in users and use a different end point for it, or return a "filler" when the user do not have permission to access the data.

(and it is always a bad idea to make modifications to the official rest API as you might create incompatibilities with other users of it, so at least be careful use prefixes etc)