wcml_variation_term_taxonomy_ids

/**
 * This example is extracted from the WooCommerce Subscriptions compatibility class in the WCML code. 
 * This WooCommerce extension has its own variable product type called "variable-subscription"
 */

add_filter('wcml_variation_term_taxonomy_ids', 'add_wcml_variation_term_taxonomy_ids');

function add_wcml_variation_term_taxonomy_ids($get_variation_term_taxonomy_ids){
    global $wpdb;
    $get_variation_term_taxonomy_id = $wpdb->get_var("SELECT tt.term_taxonomy_id FROM $wpdb->terms AS t LEFT JOIN $wpdb->term_taxonomy AS tt ON t.term_id = tt.term_id WHERE t.slug = 'variable-subscription'");
    
    if(!empty($get_variation_term_taxonomy_id)){
        $get_variation_term_taxonomy_ids[] = $get_variation_term_taxonomy_id;    
    }
    
    return $get_variation_term_taxonomy_ids;
}