Change class-name on "current_ancestor" in wp_nav_menu

Question

Im working with a project where i want the wp_nav_menu to output other css classes for current_page, current_ancestor and remove other stuff like page-id and menu-id.

I have get some stuff working like remove the unessesary classes and id:s using a custom Walker. But i cant get the current_ancestor to change to another class.

here is what i have come up with until now:

class Clean_Walker extends Walker_Nav_Menu 
{

    /**
     * @see Walker::start_el()
     * @since 3.0.0
     *
     * @param string $output Passed by reference. Used to append additional content.
     * @param object $item Menu item data object.
     * @param int $depth Depth of menu item. Used for padding.
     * @param int $current_page Menu item ID.
     * @param object $args
     */

    function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) 
    {
        global $wp_query;

        $class_names = $value = '';

        $classes[] = ( $item->current ) ? 'sel' : '';


        // $current_classes = array(
        //     'current-menu-item',
        //     'current-menu-parent',
        //     'current-menu-ancestor',
        //     'current_page_item',
        //     'current_page_parent',
        //     'current_page_ancestor'
        // );

        // foreach ($current_classes as $current_class )
        //  {
        //     if ( in_array( $current_class, $classes ) ) 
        //     {
        //         $classes[] = "active";
        //         break;
        //     }
        // }


        $class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args ) );

        $class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';


        $output .= '<li'. $class_names .'>';

        $attributes  = ! empty( $item->attr_title ) ? ' title="'  . esc_attr( $item->title .' '. $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        ) .'"' : '';


        $attribute  = ! empty( $item->attr_title ) ? '<span>' . esc_attr( $item->attr_title ) . '</span>' : '';

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

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

I also needed the attribute-field to be inside a span for some styling. So the poblem is that i need to change "current_ancestor" to the class sel.

The class sel are working on a "single-page" so the only problem comes when im one lvl deeper.

I have search WPSE but no luck. Thanks!

Answer 1

I believe the current-ancestor etc. classes are not added by the walker itself, but rather by wp_nav_menu which is calling _wp_menu_item_classes_by_context. Thus, your best bet is probably to add a filter to nav_menu_css_class and remove/replace current-* classes as needed. In its most basic form, something like:

function my_navigation_class($classes, $item){
    foreach ($classes as $idx => $class) {
        if ($class == 'current_ancestor') {
            $classes[$idx] = 'sel';
        }
    }
    return $classes;
}
add_filter('nav_menu_css_class' , 'my_navigation_class' , 10 , 2);

Answer 2

Removes ids and classes except those from $current_indicators array. You can easily add/remove classes there. Then apply @Simon's filter.

// based on http://snipplr.com/view/58549/
class Clnr_Walker_Nav_Menu extends Walker_Nav_Menu {
    function start_el(&$output, $item, $depth, $args) {
        //~ pre($item);
        global $wp_query;
        $indent = ($depth) ? str_repeat('\t',$depth) : '';
        $class_names = '';
        $classes = empty($item->classes) ? array() : (array) $item->classes;
        $current_indicators = array(
            'current-menu-item',
            'current-menu-parent',
            'current-menu-ancestor',
            'current_page_item',
            'current_page_parent',
            'current-page-ancestor' // see Feb 20 update below
        );
        $newClasses = array();
        foreach($classes as $el) {
            if( in_array($el, $current_indicators) ) {
                array_push($newClasses, $el);
            }
        }
        $class_names = join( ' ', apply_filters('nav_menu_css_class', array_filter($newClasses), $item) );

        $output .= $indent . '<li class="' . $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) . '"' : '';

        if($depth != 0) {
            //children stuff, maybe you'd like to store the submenu's somewhere?
        }

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

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

Updated (February 20):

There seems to be a bug in Wordpress 3.5.1 (at least). There is no such class as current_page_ancestor (underscore-separated) any more, it's current-page-ancestor (dash-separated) instead. I don't have the time right now to figure out the cause of this, but looks like it is in _wp_menu_item_classes_by_context() inside /wp-includes/nav-menu-template.php.