Custom markup with wp_nav_menu based on pages

Question

How might I have custom markup for my menus, like I want to give menu items something like id="menuitem-postname" how might I do that?

Answer 1

The only way that I could think to do this would be to add a filter to wp_nav_menu_items. Here is the code that I got to work (just add it to your themes functions.php file):

add_filter('wp_nav_menu_items', 'my_id_name_nav', 10, 2);
function my_id_name_nav($items,$args) {
  if( $args->theme_location == 'primary' ) {
    preg_match_all('/<li id="menu-item-([0-9]+)"([^>]+)>\s*<a href="([^"]+)">([^<]+)<\/a><\/li>/i', $items, $matches);
    $newItems = array();
    for($i=0; $i<count($matches[0]); $i++){
      $short = explode('/', $matches[3][$i]);
      $short = $short[count($short) - 2]; // if there is no trailing slash, subtract 1 instead of 2
      array_push($newItems, '<li id="menu-item-'. $short .'"'. $matches[2][$i] .'><a href="'. $matches[3][$i] .'">'. $matches[4][$i] .'</a></li>');
    }
    return implode('', $newItems);
  } else {
    return $items;
  }
}

It uses the last part of the url to create the page name for the id. So menu-item-2 for http://yoursite.com/page1/page2/ would become menu-item-page2.

The if( $args->theme_location == 'primary' ) is for targeting a specific menu. If you want to do this for all menus just remove the if else statement.

Answer 2

Very Simple ... Use a Custom Walker ... All you need to do is attach something constant to the id element ... such as the actual post or page id ... That's in the menu_item->object_id ... I don't really see why your doing this though ... with a cursory knowledge of CSS you can easily utilize the cascade to address an items children ... All the menu_items are already assigned css classes ... @see the Codex

$args = array (

'theme_location'  => 'primary',
'menu'            => 'Menu Name',
'container'       => 'div',
'container_class' => 'nav',
'container_id'    => FALSE,
'menu_class'      => FALSE,
'menu_id'         => FALSE,
'echo'            => TRUE,
'fallback_cb'     => 'wp_page_menu',
'before'          => FALSE,
'after'           => FALSE,
'link_before'     => FALSE,
'link_after'      => FALSE,
'items_wrap'      => "\n\t" . '<ul>%3$s</ul>' . "\n",
'depth'           => 0,
'walker'          => new ID_Walker()
);

wp_nav_menu( $args );

class ID_Walker extends Walker_Nav_Menu {

function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
    global $wp_query;
    $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';

    $class_names = $value = '';

    $classes = empty( $item->classes ) ? array() : (array) $item->classes;
    $classes[] = 'menu-item-' . $item->ID;

    $class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args ) );
    $class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';

    $id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args );

            /** 
            * Add the object id as a reference
            * This will tie your menu_item id ref to your post page or cpt
            */  

    $oid = esc_attr( $item->object_id ); 

            /**
            * Append the object id to the element id  
            */

    $id = $id ? ' id="' . esc_attr( $id ) . '-' . $oid . '"' : '';

    $output .= $indent . '<li' . $id . $value . $class_names .'>';

    $attributes  = ! empty( $item->attr_title ) ? ' title="'  . esc_attr( $item->attr_title ) .'"' : '';
    $attributes .= ! empty( $item->target )     ? ' target="' . esc_attr( $item->target     ) .'"' : '';
    $attributes .= ! empty( $item->xfn )        ? ' rel="'    . esc_attr( $item->xfn        ) .'"' : '';
    $attributes .= ! empty( $item->url )        ? ' href="'   . esc_attr( $item->url        ) .'"' : '';

    $item_output = $args->before;
    $item_output .= '<a' . $attributes .'>';
    $item_output .= $args->link_before . apply_filters( 'the_title', $item->title, $item->ID ) . $args->link_after;
    $item_output .= '</a>';
    $item_output .= $args->after;

    $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
    }
}