get FIRST parent of a page

Avoiding a loop could be great too…

Sorry, it can’t be done without looping or making a recursive call (which is the same basic thing).

Something like this would do it:

function get_root_parent($page_id) {
	$parent = $wpdb->get_var("SELECT post_parent FROM $wpdb->posts WHERE post_type='page' AND ID = '$page_id'");
	if ($parent == 0) return $page_id;
	else return get_root_parent($parent);
}

Basically, you give it a page id and get back the root parent. But it has to navigate its way up through the pages to find the root.

Okay, thanks !
But this isn’t working.
Maybe a typo somewhere ?

function get_root_parent($page_id) {
				$query = 'SELECT post_parent FROM $wpdb->posts WHERE post_type="page" AND ID = "'.$page_id.'"';
				$parent = $wpdb->get_var($query);
				if ($parent == 0) return $page_id;
				else return get_root_parent($parent);
			}

$parent_page = $post->post_parent;
get_root_parent($parent_page);

Fatal error: Call to a member function get_var() on a non-object in /menu.php on line 11

This is WordPress code. It has to be run as part of WordPress. What is “menu.php”? That’s not part of WordPress, is it?

no, it is one of my templates included

Try adding global $wpdb; as the first line in the function.

function get_root_parent($page_id) {
global $wpdb;
	$parent = $wpdb->get_var("SELECT post_parent FROM $wpdb->posts WHERE post_type='page' AND ID = '$page_id'");
	if ($parent == 0) return $page_id;
	else return get_root_parent($parent);
}

Ok, this one works.
Thanks, Otto42 !

hmm, sounds good.
how do you use this to highlight the topmost parent in a menu structure?
is there a code you add to the wp_list_pages call in the header to keep the “grandparent” highlighted?

this is a piece of my menu where it "happens" :)

		$onglets = wp_list_pages('title_li=&depth=1&echo=0');

		$onglets = explode("<a href=\"", $onglets);

		for($i=1;$i<sizeof($onglets);$i++) {

			$ongletclass = "";

			$onglet_url = explode("\">", $onglets[$i]);

			$onglet_url2 = explode("\" title=\"", $onglet_url[0]);

			$onglet_title = $onglet_url2[1];

			$onglet_vars = explode("?", $onglet_url2[0]);

			$onglet_vars = "&".$onglet_vars[1];

			parse_str($onglet_vars, $output);

			//ID PAGE ONGLET

			$onglet_id = $output['page_id'];  // value

			if ( (is_page()) && (empty($onglet_id)) ) { //bug de la HOME qui n'affiche pas de var page_id;

				$onglet_id = $post->ID;

			}

			if (($root_page) == $onglet_id){

				$ongletclass ='class="default"';

			}

			echo'<dl '.$ongletclass.'><dt id="onglet'.$i.'">';

okay, looks like you use the url to see how deep you are.
thanks for the code … but i don’t think i can use it.
but someone else might ??