A secondary menu for specific pages/subpages

I wanted to share my solution for getting a menu for certain pages. I have a webpage with events, a blog and general pages. The blog is shared over all events, but the event-pages needed their own menu.

So I wanted to have a WP3-menu shown only when in the tree of a certain event. My solution is “if the name of the parent equals to the name of a menu, then show that menu. If there is no such menu defined or when on the top-page, show nothing”. For each event I make a new WP3-menu with exactly the same name as the event’s first page – the below code allows me to show only a menu if that part of the page has a menu defined. So for instance, the about-page does not trigger it.

<?php
	// get the parent-page - this page defines the 'region'
	$parents = get_post_ancestors( $post->ID );
	$region_id = ($parents) ? $parents[count($parents)]: $post->ID;
	// get the name from the id
	$region = get_page( $region_id );
	$region_name = $region->post_name;
	//echo "[".$region_name."]";
	// show the menu when it exists
	if (strlen($region_name)>0 && wp_get_nav_menu_object($region_name) ) {
	// change below to fit your own need. Only 'menu' is important
	wp_nav_menu( array('menu' => $region_name, 'container' => '', 'container_class' => '', 'menu_class' => '', 'menu_id' => 'menuhead', 'sort_column' => 'menu_order') );
}
?>

As you see, finally a good reason to have multiple menus. Hopefully I have helped somebody. To know how it looks like, take a look at https://www.platformparallel.nl/.