wordpress 自定义菜单

有时候我们需要在菜单里加入额外的一些元素，可以用Walker_Nav_Menu类来完成。

class description_walker extends Walker_Nav_Menu {
 function start_el(&$output, $item, $depth, $args) {
 global $wp_query;
 global $wpdb;
 $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="' . esc_attr( $class_names ) . '"';
 
 $id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args );
 $id = strlen( $id ) ? ' id="' . esc_attr( $id ) . '"' : '';
 
 $output .= $indent . '<li' . $id . $value . $class_names .'>';
 
 $prepend = '';
 $append = '';
 $description = ! empty( $item->attr_title ) ? '' . esc_attr( $item->attr_title ) . '' : '';
 
 if($depth != 0) {
 $description = $append = $prepend = "";
 $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( $item->url ) ? ' href="'%20.%20esc_attr(%20$item->url%20)%20.'"' : '';
 
 $item_output = $args->before;
 $item_output .= '<a'. $attributes .'><i class="'.$description.'"></i>';
 $item_output .= $args->link_before . $prepend . apply_filters( 'the_title', $item->title, $item->ID ) . $append;
 $item_output .= $args->link_after;
 
 $has_children = $wpdb -> get_var( "SELECT COUNT(meta_id) FROM {$wpdb->prefix}postmeta WHERE meta_key='_menu_item_menu_item_parent' AND meta_value='" . $item->ID . "'" );
 if ($has_children > 0) { //如果有二级菜单
 $item_output .= '<span class="arrow"></span>';
 }
 $item_output .= '</a>';
 $item_output .= $args->after;
 
 $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
 }
}

给当前菜单添加class

function special_nav_class($classes, $item){
 if( in_array('current-menu-item', $classes) || in_array('current-menu-ancestor', $classes) || in_array('current-post-parent', $classes) || in_array('current-post-ancestor', $classes)){
 $classes[] = 'active ';
 }
 return $classes;
}
add_filter('nav_menu_css_class' , 'special_nav_class' , 10 , 2);