我试图制作非标准的主导航菜单并坚持使用子菜单项，根据大多数教程和wordpress指南，walker类使用简单的菜单类型，如：
<ul>
<li><a>Menu Item</a></li>
<li><a>Menu Item</a>
<ul>
<li><a>Submenu Item</a></li>
</ul>
</li>
</ul>
哪个不适合我的菜单结构：
<ul class="navbar-nav">
<li class="nav-item">
<a class="nav-link">
<i class="nav-icons home_icon"></i>
<p>Home</p>
</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
<i class="nav-icons catalog_icon"></i>
<p>Catalog</p>
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
<a class="dropdown-item">Catalog 1</a>
<a class="dropdown-item">Catalog 2</a>
</div>
</li>
</ul>
我知道walker类用4个函数（start_lvl，start_el，end_el，end_lvl）形成菜单，但有没有任何教程或任何其他有关如何制作simillar的信息，或者有人可以提供代码示例来实现我需要的结果？我的菜单只包含1个子菜单级别。
这对于Bootstrap导航菜单walker类，
if (!class_exists('BootstrapBasicMyWalkerNavMenu')) {
class BootstrapBasicMyWalkerNavMenu extends Walker_Nav_Menu
{
//Overwrite display_element function to add has_children attribute. Not needed in >= Wordpress 3.4
/**
* @link https://gist.github.com/duanecilliers/1817371 copy from this url
*/
function display_element($element, &$children_elements, $max_depth, $depth = 0, $args, &$output)
{
if (!$element)
return;
$id_field = $this->db_fields['id'];
//display this element
if (is_array($args[0]))
$args[0]['has_children'] = !empty($children_elements[$element->$id_field]);
else if (is_object($args[0]))
$args[0]->has_children = !empty($children_elements[$element->$id_field]);
$cb_args = array_merge(array(&$output, $element, $depth), $args);
call_user_func_array(array(&$this, 'start_el'), $cb_args);
$id = $element->$id_field;
// descend only when the depth is right and there are childrens for this element
if (($max_depth == 0 || $max_depth > $depth + 1) && isset($children_elements[$id])) {
foreach ($children_elements[$id] as $child) {
if (!isset($newlevel)) {
$newlevel = true;
//start the child delimiter
$cb_args = array_merge(array(&$output, $depth), $args);
call_user_func_array(array(&$this, 'start_lvl'), $cb_args);
}
$this->display_element($child, $children_elements, $max_depth, $depth + 1, $args, $output);
}
unset($children_elements[$id]);
}
if (isset($newlevel) && $newlevel) {
//end the child delimiter
$cb_args = array_merge(array(&$output, $depth), $args);
call_user_func_array(array(&$this, 'end_lvl'), $cb_args);
}
//end this element
$cb_args = array_merge(array(&$output, $element, $depth), $args);
call_user_func_array(array(&$this, 'end_el'), $cb_args);
}// display_element
/**
* @link https://gist.github.com/duanecilliers/1817371 copy from this url
*/
public function start_el(&$output, $item, $depth = 0, $args = array(), $id = 0)
{
if ((is_object($item) && $item->title == null) || (!is_object($item))) {
return ;
}
$indent = ($depth) ? str_repeat("\t", $depth) : '';
$li_attributes = '';
$class_names = $value = '';
$classes = empty($item->classes) ? array() : (array) $item->classes;
//Add class and attribute to LI element that contains a submenu UL.
if (is_object($args) && $args->has_children) {
//$classes[] = 'dropdown';
$li_attributes .= ' data-dropdown="dropdown"';
}
$classes[] = 'menu-item-' . $item->ID;
//If we are on the current page, add the active class to that menu item.
$classes[] = ($item->current) ? 'active' : '';
//Make sure you still add all of the WordPress classes.
$class_names = join(' ', apply_filters('nav_menu_css_class', array_filter($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 . $li_attributes . '>';
//Add attributes to link element.
$attributes = !empty($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) . '"' : '';
$attributes .= (is_object($args) && $args->has_children) ? ' class="dropdown-toggle" data-toggle="dropdown"' : '';
$item_output = (is_object($args)) ? $args->before : '';
$item_output .= '<a' . $attributes . '>';
$item_output .= (is_object($args) ? $args->link_before : '') . apply_filters('the_title', $item->title, $item->ID) . (is_object($args) ? $args->link_after : '');
$item_output .= (is_object($args) && $args->has_children) ? ' <span class="caret"></span> ' : '';
$item_output .= '</a>';
$item_output .= (is_object($args) ? $args->after : '');
$output .= apply_filters('walker_nav_menu_start_el', $item_output, $item, $depth, $args);
}// start_el
public function start_lvl(&$output, $depth = 0, $args = array())
{
$indent = str_repeat("\t", $depth);
$output .= "\n$indent<ul class=\"sub-menu dropdown-menu\">\n";
}
}
}
怎么用，
<?php wp_nav_menu(array('theme_location' => 'your-menu-location', 'container' => false, 'menu_class' => 'nav navbar-nav', 'walker' => new BootstrapBasicMyWalkerNavMenu())); ?>
希望这会对你有所帮助。
欲获得更多信息，