wordpress进阶教程(二十五):给菜单项添加字段

我们知道1、wordpress的文章有个自定义字段，而且在本工作室前面的教程中也有关于添加自定义字段的教程和类文件。2、wordpress的菜单也是“某一个文章类型”，类型名为nav_menu_item，可以参考：wordpress进阶教程(一):wordpress文章类型，每一个菜单项是“一篇文章”，每一个菜单就是“一个分类”，分类法为nav_menu。

申明：本文中的代码搜集自互联网。

那么在wordpress中，菜单也可以添加自定义字段。

菜单在后台的显示代码在wp-admin/includes/nav-menu.php文件中，在类Walker_Nav_Menu_Edit很容易在里面找到后台菜单项的显示代码，但是寻找后发现，代码中并没有提供过滤器或者动作钩子。

方法：

一、将wp-admin/includes/nav-menu.php文件中Walker_Nav_Menu_Edit类复制一份粘贴到主题functions.php文件中，更改类名，然后在里面添加相应的代码。如下：

Walker_Nav_Menu_Edit_Custom Walker_Nav_Menu {
/**
* @see Walker_Nav_Menu::start_lvl()
* @since 3.0.0
*
* @param string $output Passed by reference.
*/
start_lvl(&$output) {}
/**
* @see Walker_Nav_Menu::end_lvl()
* @since 3.0.0
*
* @param string $output Passed by reference.
*/
end_lvl(&$output) {
}
/**
* @see Walker::start_el()
* @since 3.0.0
*
* @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. Used for padding.
* @param object $args
*/
start_el(&$output, $item, $depth, $args) {
$_wp_nav_menu_max_depth;
$_wp_nav_menu_max_depth = $depth > $_wp_nav_menu_max_depth ? $depth : $_wp_nav_menu_max_depth;
$indent = ( $depth ) ? str_repeat( “t”, $depth ) : ”;
ob_start();
$item_id = esc_attr( $item->ID );
$removed_args = (
‘action’,
‘customlink-tab’,
‘edit-menu-item’,
‘menu-item’,
‘page-tab’,
‘_wpnonce’,
);
$original_title = ”;
( ‘taxonomy’ == $item->type ) {
$original_title = get_term_field( ‘name’, $item->object_id, $item->object, ‘raw’ );
( is_wp_error( $original_title ) )
$original_title = false;
} ( ‘post_type’ == $item->type ) {
$original_object = get_post( $item->object_id );
$original_title = $original_object->post_title;
}
$classes = (
‘menu-item menu-item-depth-‘ . $depth,
‘menu-item-‘ . esc_attr( $item->object ),
‘menu-item-edit-‘ . ( ( isset( $_GET[‘edit-menu-item’] ) && $item_id == $_GET[‘edit-menu-item’] ) ? ‘active’ : ‘inactive’),
);
$title = $item->title;
( ! ( $item->_invalid ) ) {
$classes[] = ‘menu-item-invalid’;
/* translators: %s: title of menu item which is invalid */
$title = sprintf( __( ‘%s (Invalid)’ ), $item->title );
} ( isset( $item->post_status ) && ‘draft’ == $item->post_status ) {
$classes[] = ‘pending’;
/* translators: %s: title of menu item in draft status */
$title = sprintf( __(‘%s (Pending)’), $item->title );
}
$title = ( $item->label ) ? $title : $item->label;
?>
<li id=“menu-item-<?php echo $item_id; ?>” =“<?php echo implode(‘ ‘, $classes ); ?>”>
<dl =“menu-item-bar”>
<dt =“menu-item-handle”>
<span =“item-title”><?php echo esc_html( $title ); ?></span>
<span =“item-controls”>
<span =“item-type”><?php echo esc_html( $item->type_label ); ?></span>
<span =“item-order hide-if-js”>
<a href=“<?php
echo wp_nonce_url(
add_query_arg(
array(
‘action’ => ‘move-up-menu-item’,
‘menu-item’ => $item_id,
),
remove_query_arg($removed_args, admin_url( ‘nav-menus.php’ ) )
),
‘move-menu_item’
);
?>” =“item-move-up”><abbr title=“<?php esc_attr_e(‘Move up’); ?>”>↑</abbr></a>
|
<a href=“<?php
echo wp_nonce_url(
add_query_arg(
array(
‘action’ => ‘move-down-menu-item’,
‘menu-item’ => $item_id,
),
remove_query_arg($removed_args, admin_url( ‘nav-menus.php’ ) )
),
‘move-menu_item’
);
?>” =“item-move-down”><abbr title=“<?php esc_attr_e(‘Move down’); ?>”>↓</abbr></a>
</span>
<a =“item-edit” id=“edit-<?php echo $item_id; ?>” title=“<?php esc_attr_e(‘Edit Menu Item’); ?>” href=“<?php
echo ( isset( $_GET[‘edit-menu-item’] ) && $item_id == $_GET[‘edit-menu-item’] ) ? admin_url( ‘nav-menus.php’ ) : add_query_arg( ‘edit-menu-item’, $item_id, remove_query_arg( $removed_args, admin_url( ‘nav-menus.php#menu-item-settings-‘ . $item_id ) ) );
?>”><?php _e( ‘Edit Menu Item’ ); ?></a>
</span>
</dt>
</dl>
<div =“menu-item-settings” id=“menu-item-settings-<?php echo $item_id; ?>”>
<?php ( ‘custom’ == $item->type ) : ?>
<p =“field-url description description-wide”>
<label =“edit-menu-item-url-<?php echo $item_id; ?>”>
<?php _e( ‘URL’ ); ?><br />
<input type=“text” id=“edit-menu-item-url-<?php echo $item_id; ?>” =“widefat code edit-menu-item-url” name=“menu-item-url[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( $item->url ); ?>” />
</label>
</p>
<?php ; ?>
<p =“description description-thin”>
<label =“edit-menu-item-title-<?php echo $item_id; ?>”>
<?php _e( ‘Navigation Label’ ); ?><br />
<input type=“text” id=“edit-menu-item-title-<?php echo $item_id; ?>” =“widefat edit-menu-item-title” name=“menu-item-title[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( $item->title ); ?>” />
</label>
</p>
<p =“description description-thin”>
<label =“edit-menu-item-attr-title-<?php echo $item_id; ?>”>
<?php _e( ‘Title Attribute’ ); ?><br />
<input type=“text” id=“edit-menu-item-attr-title-<?php echo $item_id; ?>” =“widefat edit-menu-item-attr-title” name=“menu-item-attr-title[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( $item->post_excerpt ); ?>” />
</label>
</p>
<p =“field-link-target description”>
<label =“edit-menu-item-target-<?php echo $item_id; ?>”>
<input type=“checkbox” id=“edit-menu-item-target-<?php echo $item_id; ?>” value=“_blank” name=“menu-item-target[<?php echo $item_id; ?>]”<?php checked( $item->target, ‘_blank’ ); ?> />
<?php _e( ‘Open link in a window/tab’ ); ?>
</label>
</p>
<p =“field-css-classes description description-thin”>
<label =“edit-menu-item-classes-<?php echo $item_id; ?>”>
<?php _e( ‘CSS Classes (optional)’ ); ?><br />
<input type=“text” id=“edit-menu-item-classes-<?php echo $item_id; ?>” =“widefat code edit-menu-item-classes” name=“menu-item-classes[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( implode(‘ ‘, $item->classes ) ); ?>” />
</label>
</p>
<p =“field-xfn description description-thin”>
<label =“edit-menu-item-xfn-<?php echo $item_id; ?>”>
<?php _e( ‘Link Relationship (XFN)’ ); ?><br />
<input type=“text” id=“edit-menu-item-xfn-<?php echo $item_id; ?>” =“widefat code edit-menu-item-xfn” name=“menu-item-xfn[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( $item->xfn ); ?>” />
</label>
</p>
<p =“field-description description description-wide”>
<label =“edit-menu-item-description-<?php echo $item_id; ?>”>
<?php _e( ‘Description’ ); ?><br />
<textarea id=“edit-menu-item-description-<?php echo $item_id; ?>” =“widefat edit-menu-item-description” rows=“3” cols=“20” name=“menu-item-description[<?php echo $item_id; ?>]”><?php echo esc_html( $item->description ); // textarea_escaped ?></textarea>
<span =“description”><?php _e(‘The description will be displayed in the menu the current theme supports it.’); ?></span>
</label>
</p>
<?php
/*
* 嘿，下面是自己添加的代码，注意里面的字符 ashuwp
*/
?>
<p =“field-ashuwp description description-wide”>
<label =“edit-menu-item-ashuwp-<?php echo $item_id; ?>”>wp自学笔记<br />
<input type=“text” id=“edit-menu-item-ashuwp-<?php echo $item_id; ?>” =“widefat code edit-menu-item-ashuwp” name=“menu-item-ashuwp[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( $item->ashuwp ); ?>” />
</label>
</p>
<?php
/*
* 自己添加的代码结束，你可以继续添加其他的字段代码
*/
?>
<div =“menu-item-actions description-wide submitbox”>
<?php ( ‘custom’ != $item->type && $original_title !== false ) : ?>
<p =“link-to-original”>
<?php printf( __(‘Original: %s’), ‘<a href=“‘ . esc_attr( $item->url ) . ‘”>’ . esc_html( $original_title ) . ‘</a>’ ); ?>
</p>
<?php ; ?>
<a =“item-delete submitdelete deletion” id=“delete-<?php echo $item_id; ?>” href=“<?php
echo wp_nonce_url(
add_query_arg(
array(
‘action’ => ‘delete-menu-item’,
‘menu-item’ => $item_id,
),
remove_query_arg($removed_args, admin_url( ‘nav-menus.php’ ) )
),
‘delete-menu_item_’ . $item_id
); ?>”><?php _e(‘Remove’); ?></a> <span =“meta-sep”> | </span> <a =“item-cancel submitcancel” id=“cancel-<?php echo $item_id; ?>” href=“<?php echo esc_url( add_query_arg( array(‘edit-menu-item’ => $item_id, ‘cancel’ => time()), remove_query_arg( $removed_args, admin_url( ‘nav-menus.php’ ) ) ) );
?>#menu-item-settings-<?php echo $item_id; ?>”><?php _e(‘Cancel’); ?></a>
</div>
<input =“menu-item-data-db-id” type=“hidden” name=“menu-item-db-id[<?php echo $item_id; ?>]” value=“<?php echo $item_id; ?>” />
<input =“menu-item-data-object-id” type=“hidden” name=“menu-item-object-id[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( $item->object_id ); ?>” />
<input =“menu-item-data-object” type=“hidden” name=“menu-item-object[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( $item->object ); ?>” />
<input =“menu-item-data-parent-id” type=“hidden” name=“menu-item-parent-id[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( $item->menu_item_parent ); ?>” />
<input =“menu-item-data-position” type=“hidden” name=“menu-item-position[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( $item->menu_order ); ?>” />
<input =“menu-item-data-type” type=“hidden” name=“menu-item-type[<?php echo $item_id; ?>]” value=“<?php echo esc_attr( $item->type ); ?>” />
</div><!– .menu-item-settings–>
<ul =“menu-item-transport”></ul>
<?php
$output .= ob_get_clean();
}
}

二、修改默认的walker类为新类：

//该过滤器位于nav-menu.php
add_filter( ‘wp_edit_nav_menu_walker’, ‘custom_nav_edit_walker’,10,2 );
custom_nav_edit_walker($walker,$menu_id) {
‘Walker_Nav_Menu_Edit_Custom’;//新类名
}

注意上面新类代码中有一段新添加的代码，以及类名修改为Walker_Nav_Menu_Edit_Custom，至此新类就启用了。

三、数据的保存和更新：

//注意下面代码中的字符 ashuwp
add_action(‘wp_update_nav_menu_item’, ‘custom_nav_update’,10, 3);
custom_nav_update($menu_id, $menu_item_db_id, $args ) {
( is_array($_REQUEST[‘menu-item-ashuwp’]) ) {
$custom_value = $_REQUEST[‘menu-item-ashuwp’][$menu_item_db_id];
update_post_meta( $menu_item_db_id, ‘_menu_item_ashuwp’, $custom_value );
}
}
add_filter( ‘wp_setup_nav_menu_item’,’custom_nav_item’ );
custom_nav_item($menu_item) {
$menu_item->ashuwp = get_post_meta( $menu_item->ID, ‘_menu_item_ashuwp’, true );
$menu_item;
}