Set of functions for storing and getting last modified timestamps for WordPress menus

save-menu-date-modified-timestamps.php

<?php

/**
 * Save the date modified timestamp for a WordPress menu.
 *
 * @param int $menu_id Term ID of the menu being created/updated.
 */
function wds_save_menu_modified_timestamp( $menu_id ) {

	$modified_timestamps             = get_option( '_wds_menu_modified', array() );
	$modified_timestamps[ $menu_id ] = current_time( 'timestamp' );

	update_option( '_wds_menu_modified', $modified_timestamps, false );
}
add_action( 'wp_create_nav_menu', 'wds_save_menu_modified_timestamp' );
add_action( 'wp_update_nav_menu', 'wds_save_menu_modified_timestamp' );

/**
 * Delete the date modified timestamp for a WordPress menu.
 *
 * @param int $menu_id Term ID of the menu being deleted.
 */
function wds_delete_menu_modified_timestamp( $menu_id ) {

	$modified_timestamps = get_option( '_wds_menu_modified', array() );

	// Bail if this menu ID doesn't exist in the array of date modified timestamps.
	if ( ! isset( $modified_timestamps[ $menu_id ] ) ) {
		return;
	}

	unset( $modified_timestamps[ $menu_id ] );
	update_option( '_wds_menu_modified', $modified_timestamps, false );
}
add_action( 'wp_delete_nav_menu', 'wds_delete_menu_modified_timestamp' );

/**
 * Get the date modified timestamp for a WordPress menu.
 *
 * @param  int        $menu_id Term ID of the menu.
 *
 * @return int|string          The date modified timestamp or empty string, if none.
 */
function wds_get_menu_modified_timestamp( $menu_id ) {

	$modified_timestamps = get_option( '_wds_menu_modified', array() );

	// Return an emtpy string if this menu ID doesn't exist in the array of date modified timestamps.
	if ( ! isset( $modified_timestamps[ $menu_id ] ) ) {
		return '';
	}

	return $modified_timestamps[ $menu_id ];
}