automatically select parent terms

[WP] Automatically select parent terms

add_action('set_object_terms', 'auto_set_parent_terms',  9999, 6); // automatically select parent terms
function auto_set_parent_terms( $object_id, $terms, $tt_ids, $taxonomy, $append, $old_tt_ids ) {

    foreach( $tt_ids as $tt_id ) {
        if ($parenttags = get_ancestors($tt_id, $taxonomy))
        {
            wp_set_object_terms( $object_id, $parenttags, $taxonomy, true );
        }
    }
}