Exclude pages from wp_list_pages

mx_hide_from_list_pages.php

function mx_hide_from_list_pages( $exclude_array ) {
	global $wpdb;
	$table = _get_meta_table('post');
	$sql = "SELECT post_id FROM " . $table . " WHERE meta_key ='_smartmeta_navigation_hide' AND meta_value ='true'";
	$id_array = $wpdb->get_col($sql);
	$exclude_array = array_merge($id_array, $exclude_array);
	return $exclude_array;
}
add_filter( 'wp_list_pages_excludes', 'mx_hide_from_list_pages' );