wordpress进阶教程(三十五)：给菜单加上分隔线或者分隔字符

很多网页设计都会给菜单之间加一个分割线，最常见的就是“|”了，如图：

我们需要的是，每个菜单项之间有一个分隔符。传统的方法是配置wordpress的菜单输出函数wp_nav_menu，给它加上一个after参数，

<?php
$args = (
‘after’=>’|’ //菜单项后面加|字符
);
wp_nav_menu($args);
?>

这样可以给每个菜单项的后面加一个字符，且html结构如下

<ul>
<li><a href=“”>wp自学笔记</a>|</li>
<li><a href=“”>wp自学笔记</a>|</li>
<li><a href=“”>wp自学笔记</a>|</li>
</ul>

这样有个显而易见的缺点就是每个菜单项后面都有个竖线，最后一个菜单项也有，可是我们肯定不需要菜单的最后面也出现竖线，当然这样的结构，通过css还是可以写出上面图片中的样式的。

我们要的效果：每个菜单项后面加一个分割线，菜单的最后面不要，二级菜单不要。

分析：wp_nav_menu函数输出菜单项的代码在 wp-includes/nav-menu-template.php文件里面，具体的呢，在文件中Walker_Nav_Menu类里面的start_el函数，所以，方法就是改造这个函数。

步骤一：找到wp_nav_menu函数，增加一个walker参数，如下：

<?php
$args = (
‘depth’=>2, //支持二级菜单
‘walker’ => ashuwp_navwalker(), //后面的ashuwp_navwolker是类名
‘theme_location’ => ‘ashuwp-menu’ //注意这个theme-location参数
);
wp_nav_menu($args);
?>

关于walker参数的用法，请参考官网。

步骤二：前面的代码中walker参数的值，后面是一个类，类名是ashuwp_navwolker，所以第二部就是新建这个类，如下：

//定义ashuwp_navwalker类，继承wp-includes/nav-menu-template.php文件中的Walker_Nav_Menu
ashuwp_navwalker Walker_Nav_Menu {
//在中间添加函数，直接复制Walker_Nav_Menu类的start_el函数进来
}

新定义一个ashuwp_navwalker类，继承wp-includes/nav-menu-template.php文件中的Walker_Nav_Menu，然后将Walker_Nav_Menu类的start_el函数直接复制进去，复制完后，如下：

//定义ashuwp_navwalker类，继承wp-includes/nav-menu-template.php文件中的Walker_Nav_Menu
ashuwp_navwalker Walker_Nav_Menu {
//在中间添加函数，直接复制Walker_Nav_Menu类的start_el函数进来
start_el( &$output, $item, $depth = 0, $args = (), $id = 0 ) {
$indent = ( $depth ) ? str_repeat( “t”, $depth ) : ”;
$class_names = $value = ”;
$classes = ( $item->classes ) ? () : () $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 ? ‘ =“‘ . 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 . $class_names .’>’;
$atts = ();
$atts[‘title’] = ! ( $item->attr_title ) ? $item->attr_title : ”;
$atts[‘target’] = ! ( $item->target ) ? $item->target : ”;
$atts[‘rel’] = ! ( $item->xfn ) ? $item->xfn : ”;
$atts[‘href’] = ! ( $item->url ) ? $item->url : ”;
$atts = apply_filters( ‘nav_menu_link_attributes’, $atts, $item, $args );
$attributes = ”;
( $atts $attr => $value ) {
( ! ( $value ) ) {
$value = ( ‘href’ === $attr ) ? esc_url( $value ) : esc_attr( $value );
$attributes .= ‘ ‘ . $attr . ‘=“‘ . $value . ‘”‘;
}
}
$item_output = $args->before;
$item_output .= ‘<a’. $attributes .’>’;
$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 );
}
}

步骤三：改造ashuwp_navwalker类中的start_el函数。

1.在start_el函数开头，定义一个静态数组变量，用来计数，用数组可以支持多个菜单。注意数组中的初始值，需要支持多少个菜单，都需要手动加上，静态变量用来记每个输出的菜单里面的一级菜单的数量。

//定义ashuwp_navwalker类，继承wp-includes/nav-menu-template.php文件中的Walker_Nav_Menu
ashuwp_navwalker Walker_Nav_Menu {
//在中间添加函数，直接复制Walker_Nav_Menu类的start_el函数进来
start_el( &$output, $item, $depth = 0, $args = (), $id = 0 ) {
//定义静态变量$top_level_count 数组中的值对应多个wp_nav_menu函数中的theme_location参数的值
$top_level_count = (‘ashuwp-menu’=>0,’ashuwp-nav’=>0);
//……

2.添加计算菜单中一级菜单数量的函数。该函数不需要放入类中，随便放在主题的functions.php文件的某一位置。

//参数$menu_id为菜单id
ashuwp_count_top_level_menu_items($menu_id){
$count = 0;
$menu_items = wp_get_nav_menu_items($menu_id);
($menu_items $menu_item){
($menu_item->menu_item_parent==0){
$count++;
}
}
$count;
}

3.重新定义$args-after的值，将下面的代码加入start_el函数中。

/***add code****/
$args->after=”;
($item->menu_item_parent==0 $top_level_count[$args->theme_location]!==null){ //Count top level menu items
$top_level_count[$args->theme_location]++; //Increment
}
$location_name = $args->theme_location;
( ( $locations = get_nav_menu_locations() ) && isset( $locations[ $location_name ] ) ) {
$main_nav = wp_get_nav_menu_object( $locations[ $location_name ] );
($item->menu_item_parent==0 && $top_level_count[$args->theme_location]!=ashuwp_count_top_level_menu_items($main_nav->term_id)){
$args->after= ‘|’;
}
}
/*****add code*****/

做好1 3两个点之后， ashuwp_navwalker extends类如下：

//定义ashuwp_navwalker类，继承wp-includes/nav-menu-template.php文件中的Walker_Nav_Menu
ashuwp_navwalker Walker_Nav_Menu {
//在中间添加函数，直接复制Walker_Nav_Menu类的start_el函数进来
start_el( &$output, $item, $depth = 0, $args = (), $id = 0 ) {
//定义静态变量$top_level_count 数组中的值对应多个wp_nav_menu函数中的theme_location参数的值
$top_level_count = (‘ashuwp-menu’=>0,’ashuwp-nav’=>0);
$indent = ( $depth ) ? str_repeat( “t”, $depth ) : ”;
$class_names = $value = ”;
$classes =( $item->classes ) ? () : () $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 ? ‘ =“‘ . 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 . $class_names .’>’;
$atts = ();
$atts[‘title’] = ! ( $item->attr_title ) ? $item->attr_title : ”;
$atts[‘target’] = ! ( $item->target ) ? $item->target : ”;
$atts[‘rel’] = ! ( $item->xfn ) ? $item->xfn : ”;
$atts[‘href’] = ! ( $item->url ) ? $item->url : ”;
$atts = apply_filters( ‘nav_menu_link_attributes’, $atts, $item, $args );
$attributes = ”;
( $atts $attr => $value ) {
( ! ( $value ) ) {
$value = ( ‘href’ === $attr ) ? esc_url( $value ) : esc_attr( $value );
$attributes .= ‘ ‘ . $attr . ‘=“‘ . $value . ‘”‘;
}
}
/***add code****/
$args->after=”;
($item->menu_item_parent==0 $top_level_count[$args->theme_location]!==null){ //Count top level menu items
$top_level_count[$args->theme_location]++; //Increment
}
$location_name = $args->theme_location;
( ( $locations = get_nav_menu_locations() ) && isset( $locations[ $location_name ] ) ) {
$main_nav = wp_get_nav_menu_object( $locations[ $location_name ] );
($item->menu_item_parent==0 && $top_level_count[$args->theme_location]!=ashuwp_count_top_level_menu_items($main_nav->term_id)){
$args->after= ‘|’;
}
}
/*****add code*****/
$item_output = $args->before;
$item_output .= ‘<a’. $attributes .’>’;
$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 );
}
}

至此，就可以完成了。

懒人专用

将下列代码复制到你的主题的functions.php文件中

ashuwp_count_top_level_menu_items($menu_id){
$count = 0;
$menu_items = wp_get_nav_menu_items($menu_id);
($menu_items $menu_item){
($menu_item->menu_item_parent==0){
$count++;
}
}
$count;
}
ashuwp_navwalker Walker_Nav_Menu {
start_el( &$output, $item, $depth = 0, $args = (), $id = 0 ) {
//根据实际增加和修改下面的数组
$top_level_count = (‘ashu-menu’=>0,’top-menu’=>0);
$indent = ( $depth ) ? str_repeat( “t”, $depth ) : ”;
$class_names = $value = ”;
$classes = ( $item->classes ) ? () : () $item->classes;
$classes[] = ‘menu-item-‘ . $item->ID;
/**
* Filter the CSS class(es) applied to a menu item’s <li>.
*
* @since 3.0.0
*
* @param array $classes The CSS classes that are applied to the menu item’s <li>.
* @param object $item The current menu item.
* @param array $args An array of arguments. @see wp_nav_menu()
*/
$class_names = join( ‘ ‘, apply_filters( ‘nav_menu_css_class’, array_filter( $classes ), $item, $args ) );
$class_names = $class_names ? ‘ =“‘ . esc_attr( $class_names ) . ‘”‘ : ”;
/**
* Filter the ID applied to a menu item’s <li>.
*
* @since 3.0.1
*
* @param string The ID that is applied to the menu item’s <li>.
* @param object $item The current menu item.
* @param array $args An array of arguments. @see wp_nav_menu()
*/
$id = apply_filters( ‘nav_menu_item_id’, ‘menu-item-‘. $item->ID, $item, $args );
$id = $id ? ‘ id=“‘ . esc_attr( $id ) . ‘”‘ : ”;
$output .= $indent . ‘<li’ . $id . $value . $class_names .’>’;
$atts = ();
$atts[‘title’] = ! ( $item->attr_title ) ? $item->attr_title : ”;
$atts[‘target’] = ! ( $item->target ) ? $item->target : ”;
$atts[‘rel’] = ! ( $item->xfn ) ? $item->xfn : ”;
$atts[‘href’] = ! ( $item->url ) ? $item->url : ”;
/**
* Filter the HTML attributes applied to a menu item’s <a>.
*
* @since 3.6.0
*
* @param array $atts {
* The HTML attributes applied to the menu item’s <a>, empty strings are ignored.
*
* @type string $title The title attribute.
* @type string $target The target attribute.
* @type string $rel The rel attribute.
* @type string $href The href attribute.
* }
* @param object $item The current menu item.
* @param array $args An array of arguments. @see wp_nav_menu()
*/
$atts = apply_filters( ‘nav_menu_link_attributes’, $atts, $item, $args );
$attributes = ”;
( $atts $attr => $value ) {
( ! ( $value ) ) {
$value = ( ‘href’ === $attr ) ? esc_url( $value ) : esc_attr( $value );
$attributes .= ‘ ‘ . $attr . ‘=“‘ . $value . ‘”‘;
}
}
/***add code****/
$args->after=”;
($item->menu_item_parent==0 $top_level_count[$args->theme_location]!==null){ //Count top level menu items
$top_level_count[$args->theme_location]++; //Increment
}
$location_name = $args->theme_location;
( ( $locations = get_nav_menu_locations() ) && isset( $locations[ $location_name ] ) ) {
$main_nav = wp_get_nav_menu_object( $locations[ $location_name ] );
($item->menu_item_parent==0 && $top_level_count[$args->theme_location]!=ashuwp_count_top_level_menu_items($main_nav->term_id)){
$args->after= ‘|’;
}
}
/*****add code*****/
$item_output = $args->before;
$item_output .= ‘<a’. $attributes .’>’;
/** This filter is documented in wp-includes/post-template.php */
$item_output .= $args->link_before . apply_filters( ‘the_title’, $item->title, $item->ID ) . $args->link_after;
$item_output .= ‘</a>’;
$item_output .= $args->after;
/**
* Filter a menu item’s starting output.
*
* The menu item’s starting output only includes $args->before, the opening <a>,
* the menu item’s title, the closing </a>, and $args->after. Currently, there is
* no filter for modifying the opening and closing <li> for a menu item.
*
* @since 3.0.0
*
* @param string $item_output The menu item’s starting HTML output.
* @param object $item Menu item data object.
* @param int $depth Depth of menu item. Used for padding.
* @param array $args An array of arguments. @see wp_nav_menu()
*/
$output .= apply_filters( ‘walker_nav_menu_start_el’, $item_output, $item, $depth, $args );
}
}