如何在WordPress的菜单项中添加自定义类。下面是我的代码，它不起作用

header.php

/*Render menu*/
<div class="main-nav">
   <?php wp_nav_menu( 
     array( 
     'theme_location' => 'header-menu', 'container' => 'ul', 'menu_class' => 'nav'
     ) 
   ); 
   ?>
</div>

functions.php

/*Register menu*/
function register_main_menu(){
 register_nav_menus(array(
    'Primary' => __('Header Menu'), 'Footer' => __('Footer Menu')
 ));
}
add_action('after_setup_theme', 'register_main_menu');

/*Custom menu class*/
function add_class_to_li($classes, $item){
  $classes[] = "nav-item";
  return $classes;
}
add_filter('nav_menu_css_class', 'add_class_to_li', 10, 4);

这不会在” li”中添加” nav-item”类。有什么我需要更新的吗？

#1

你的theme_location应该与在functions.php文件中拥有的theme_location完全一样。因此, 你的阅读器菜单将是：

/*Render menu*/
<div class="main-nav">
   <?php wp_nav_menu( 
     array( 
     'theme_location' => 'Primary', //this will be Primary, not header-menu
     'container' => 'ul', 'menu_class' => 'nav'
     ) 
   ); 
   ?>
</div>