Meta Box

Hello, the metabox system is not working in the following situation:

A data management system based on CUSTOM TABLES was developed for the registration of information, for various reasons, the main one being the organization and speed of data queries.
The system was created to work with an app, aiming to send and receive data by Rest-API

At the data level it only uses CUSTOM POST-TYPES, it does not use wordpress post-types.
Uses CUSTOM TABLES for USER PROFILE data logging of post-types and data logging.

Problem with user profile data
It is working correctly via WordPress Back-office. If you create or edit the profile data in Backoffice, you record and change the data added or changed in the table correctly.

Does not work in the REST API on profile data refresh.
GET correctly queries data from the defined table (collects data)
POST does not change the data. When you run a post it does not give an error and displays the data as changed but does not record it in the created table.

GET Example
{
"id": 4,
"name": "Manuel",
"url": "",
"description": "",
"link": "https:\/\/resn.arsites.eu\/arquivo\/author\/agro",
"slug": "agro",
"meta": [],
"meta_box": {
"address": "Frango assado",
"postcode": "4512-568",
"region": "Nogueiró",
"state": "Braga",
"tel": "253123456",
"lat": "-8.56885555",
"lon": "45.5898989",
"other": "Nada a informar"
},
"_links": {
"self": [
{
"href": "https:\/\/resn.arsites.eu\/wp-json\/wp\/v2\/users\/4"
}
],
"collection": [
{
"href": "https:\/\/resn.arsites.eu\/wp-json\/wp\/v2\/users"
}
]
}
}

POST Example

"meta_box": {
"address": "Rua das Casas 12666",
"postcode": "4512-568",
"region": "Nogueiró",
"state": "Braga",
"tel": "253123456",
"lat": "-8.56885555",
"lon": "45.5898989",
"other": "Nada a informar agora"
},

Example GET after POST (nothing change)

"meta_box": {
"address": "Frango assado",
"postcode": "4512-568",
"region": "Nogueiró",
"state": "Braga",
"tel": "253123456",
"lat": "-8.56885555",
"lon": "45.5898989",
"other": "Nada a informar"
},

The example user's address is https://resn.arsites.eu/wp-json/wp/v2/users/4
If you wish I can indicate an access to the system

Thank you. I try it and now works fine. Great plugin.

Works fine, thanks to show the way. Best regards

Hello, thanks to help get it works. The concept is reverse. Post get some data from user profile. Changed code to this:

add_action( 'rest_api_init', function () {
    register_rest_field( 'post', 'ag_name', array(
        'get_callback' => function( $user ) {
            $product = get_post_meta( $user['id'], 'the_user', true );
            return get_user_meta( $product, 'ag_name', true );
        },
    ) );
    register_rest_field( 'post', 'ag_address', array(
        'get_callback' => function( $user ) {
            $product = get_post_meta( $user['id'], 'the_user', true );
            return get_user_meta( $product, 'ag_address', true );
        },
    ) );
    register_rest_field( 'post', 'ag_post_code', array(
        'get_callback' => function( $user ) {
            $product = get_post_meta( $user['id'], 'the_user', true );
            return get_user_meta( $product, 'ag_post_code', true );
        },
    ) );
} );

In the metabox field set of the article, I added a filed "the_user" with the author (user field), to identify the user fields, according to the example you have indicated. When the user is indicated, it works correctly, associating the information registered in the profile of the user with the article.

Any possibility of this field or the identification code be automatic? The user field gives not only the user but the list of all users. In json output there is already the variable "author": 123 so instead of manually set the user, I could use this.

But I do not know how to use it here:
$ product = get_post_meta ($ user ['id'], 'the_user', true);

Instead of "the_user" use the "author". The author as the id of user to get the user fields info.

Thanks a lot