WP-API - Specify which fields to return in JSON

gistfile1.txt

add_filter( 'rest_prepare_post', 'my_custom_json_fields', 12, 3 );
function my_custom_json_fields( $data, $post, $context ) {
    return [
        'title'    => $data->data['title']['rendered'],
        'link'     => $data->data['link'],
    ];
}

credit: https://github.com/WP-API/WP-API/issues/446#issuecomment-212443511