//删除文章时删除图片附件开始
    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');
    //删除文章时删除图片附件