*UPDATE*
If you want to use your method or function - just add slug
add_filter('wp_nav_menu_items','replace_class', 10, 2);
function replace_class($items, $args)
{
if ($args->menu->slug == 'your-menu-name') {
$items = preg_replace('/<a/', '<a class="custom-class"', $items);
}
return $items;
}
Original Answer:
I answered this yesterday - see my answer here
Based on the link you provided (from wordpress stackexchange)
add this code to add a custom walker to your widget menu:
function widget($args, $instance) {
// Get menu
$nav_menu = ! empty( $instance['nav_menu'] ) ? wp_get_nav_menu_object( $instance['nav_menu'] ) : false;
if ( !$nav_menu )
return;
$instance['title'] = apply_filters( 'widget_title', empty( $instance['title'] ) ? '' : $instance['title'], $instance, $this->id_base );
echo $args['before_widget'];
if ( !empty($instance['title']) )
echo $args['before_title'] . $instance['title'] . $args['after_title'];
wp_nav_menu( array( 'fallback_cb' => '', 'menu' => $nav_menu ) );
echo $args['after_widget'];
}
$defaults = array( 'menu' => '', 'container' => 'div', 'container_class' => '', 'container_id' => '', 'menu_class' => 'menu', 'menu_id' => '',
'echo' => true, 'fallback_cb' => 'wp_page_menu', 'before' => '', 'after' => '', 'link_before' => '', 'link_after' => '', 'items_wrap' => '<ul id="%1$s" class="%2$s">%3$s</ul>',
'depth' => 0, 'walker' => '', 'theme_location' => '' );
$args = wp_parse_args( $args, $defaults );
$args = apply_filters( 'wp_nav_menu_args', $args );
$args = (object) $args;
function myplugin_custom_walker( $args ) {
return array_merge( $args, array(
'walker' => new Class_Name_Walker(),
// another setting go here ...
) );
}
add_filter( 'wp_nav_menu_args', 'myplugin_custom_walker' );
then add this walker - which adds the classes to the a
class Class_Name_Walker extends Walker_Nav_Menu
{
/**
* Start the element output.
*
* @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. May be used for padding.
* @param array $args Additional strings.
* @return void
*/
function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
$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 );
$id = $id ? ' id="' . esc_attr( $id ) . '"' : '';
$output .= $indent . '<li' . $id . $value .'>';
$atts = array();
$atts['title'] = ! empty( $item->attr_title ) ? $item->attr_title : '';
$atts['target'] = ! empty( $item->target ) ? $item->target : '';
$atts['rel'] = ! empty( $item->xfn ) ? $item->xfn : '';
$atts['href'] = ! empty( $item->url ) ? $item->url : '';
$atts = apply_filters( 'nav_menu_link_attributes', $atts, $item, $args );
$attributes = '';
foreach ( $atts as $attr => $value ) {
if ( ! empty( $value ) ) {
$value = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );
$attributes .= ' ' . $attr . '="' . $value . '"';
}
}
$item_output = $args->before;
$item_output .= '<a'. $attributes .$class_names.'>';
$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 );
}
/**
* @see Walker::end_el()
* @since 3.0.0
*
* @param string $output Passed by reference. Used to append additional content.
* @param object $item Page data object. Not used.
* @param int $depth Depth of page. Not Used.
*/
function end_el( &$output, $item, $depth = 0, $args = array() ) {
$output .= "</li>
";
}
}
In your admin area go to Appearance > Menus.
On the top right of the screen click on 'Screen Options' on the bottom row - make sure 'CSS Classes' is checked.