How do I set a custom meta value when creating a post using the Wordpress REST api

Question

I am currently using the Wordpress REST API to read and write posts.

I have created a custom post type called property:

register_post_type( 'property', array(
  'labels' => array(
    'name' => 'Properties',
    'singular_name' => 'Property',
   ),
  'description' => '',
  'show_in_rest' => true,
  'public' => true,
  'menu_position' => 20,
  'supports' => array( 'title', 'editor')
));

add_action( 'init', 'property_cpt' );

And I have added a custom metabox called property_name so the it will appear in the edit post admin page:

function add_property_metaboxes(){
    add_meta_box(
        'property_name', // id
        'Name', // title
        'property_name_callback', // callback
        'property', // page
        'normal', // context
        'default' // priority
    );
}
function property_name_callback() {
    global $post;
    wp_nonce_field( basename( __FILE__ ), 'property_fields' );
    $value = get_post_meta( $post->ID, 'property_name', true );
    echo '<input name="property_name" type="text" value="' . $value . '" />';
}
add_action( 'add_meta_boxes', 'add_property_metaboxes' );

I am handling the save function for this post type:

function property_save_meta( $post_id, $post ) {
    if ( ! current_user_can( 'edit_post', $post_id ) ) {
        return $post_id;
    }
    if  ( !isset( $_POST['property_name'] ) || 
          !wp_verify_nonce( $_POST['property_fields'], basename(__FILE__) ) ) {
        return $post_id;
    }
    $events_meta['property_name'] = esc_textarea( $_POST['property_name'] );

    foreach ( $events_meta as $key => $value ) :
        if ( 'revision' === $post->post_type ) {
            return;
        }
        if ( get_post_meta( $post_id, $key, false ) ) {
            update_post_meta( $post_id, $key, $value );
        } else {
            add_post_meta( $post_id, $key, $value);
        }
        if ( ! $value ) {
            delete_post_meta( $post_id, $key );
        }
    endforeach;
}
add_action( 'save_post', 'property_save_meta', 1, 2 );

And finally I have registered property_name as a rest field:

function register_rest_fields() {
    register_rest_field('property', 'property_name', 
        array(
        'get_callback' => 'get_post_meta_cb', 
        'update_callback' => 'update_post_meta_cb', 
        'schema' => null
        )
    );
}

function get_post_meta_cb($object, $field_name, $request){
    return get_post_meta($object['id'], $field_name, true); 
}
function update_post_meta_cb($value, $object, $field_name){
    if ( ! $value || ! is_string( $value ) ) {
        return;
    }
    return update_term_meta( $object->ID, $field_name, $value );
}
add_action('rest_api_init', 'register_rest_fields');

On the front-end, I am able to fetch 'property' posts using the API and the property_name field appears correctly in the response.

I am also able to create a new post easily but I am not able to set the property_name meta field value.

Currently I am trying:

request(`${url}/wp-json/wp/v2/property`, {
    method: "POST",
    body:JSON.stringify({
        title: 'Lorem ipsum dolor sit amet',
        content: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
        status: 'publish',
        meta: {
            property_name: 'Testing'
        }
    })
});

Answer 1

(As pointed in my comment,) the problem is here:

function update_post_meta_cb($value, $object, $field_name){
    if ( ! $value || ! is_string( $value ) ) {
        return;
    }
    return update_term_meta( $object->ID, $field_name, $value );
}

where you're actually saving a post meta, but then used update_term_meta() which is for saving a term meta. :)

And (I forgot to say that) to fix it, just replace the update_term_meta() with update_post_meta(). ;)