WordPress删除文章时自动删除图片附件

/** 
 * 删除文章时删除图片附件
 */
function delete_post_and_attachments($post_ID) {
    global $wpdb;
    //删除特色图片
    $thumbnails = $wpdb->get_results("SELECT * FROM $wpdb->postmeta WHERE meta_key = '_thumbnail_id' AND post_id = $post_ID");
    foreach ($thumbnails as $thumbnail) {
        wp_delete_attachment($thumbnail->meta_value, true);
    }
    //删除图片附件
    $attachments = $wpdb->get_results("SELECT * FROM $wpdb->posts WHERE post_parent = $post_ID AND post_type = 'attachment'");
    foreach ($attachments as $attachment) {
        wp_delete_attachment($attachment->ID, true);
    }
    $wpdb->query("DELETE FROM $wpdb->postmeta WHERE meta_key = '_thumbnail_id' AND post_id = $post_ID");
}
add_action('before_delete_post', 'delete_post_and_attachments');