wordpress wp_get_archives で指定した月だけ取得する

gistfile1.php

/**
 * 月を指定してwp_get_archivesを呼び出します
 * @see common-sidebar.php
 * @see wp-includes/general-template.php wp_get_archives()
 */
if ( ! function_exists( 'my_custom_post_type_archive_where' ) ) {
        function my_custom_post_type_archive_where( $where, $args ){

                if ($args['type'] != 'monthly')
                        return $where;

                if (!isset($args['year']) || !is_numeric($args['year']))
                        return $where;

                $where .= " AND YEAR(post_date) = '" . $args['year'] . "'";

                return $where;
        }
}
add_filter( 'getarchives_where', 'my_custom_post_type_archive_where', 10, 2 );