gistfile1.aw

<?php

/**
 * This is a version of
 * http://www.viper007bond.com/2011/09/20/code-snippet-add-a-link-to-latest-post-to-wordpress-nav-menu/
 * that supports multiple placeholders. In this case, the placeholder fetches
 * the latest post from a particular category.
 */

// Front end only, don't hack on the settings page
if ( ! is_admin() ) {
	// Hook in early to modify the menu
	// This is before the CSS "selected" classes are calculated
	add_filter( 'wp_get_nav_menu_items', 'replace_placeholder_nav_menu_item_with_latest_post', 10, 3 );
}

// Replaces a custom URL placeholder with the URL to the latest post
function replace_placeholder_nav_menu_item_with_latest_post( $items, $menu, $args ) {

	// Loop through the menu items looking for placeholder(s)
	foreach ( $items as $item ) {

		$args = array(
			'numberposts' => 1,
		);

		switch ( $item->url ) {

			case '#latestpost-category-abc':
				$args['category'] = 4;
				break;

			case '#latestpost-category-some-other-cat':
				$args['category'] = 123;
				break;

			// Not one of our placeholders
			default;
				continue 2;
		}

		// Get the latest post
		$latestpost = get_posts( $args );

		if ( empty( $latestpost ) )
			continue;

		// Replace the placeholder with the real URL
		$item->url = get_permalink( $latestpost[0]->ID );
	}

	// Return the modified (or maybe unmodified) menu items array
	return $items;
}