不了解插件，但只需使用两个钩子和回调函数即可轻松实现：首先，使用register_form 挂钩：

add_action(\'register_form\',\'show_reff_field\');
function show_reff_field(){ ?>
    <input id="ref" type="text" tabindex="20" size="25" value= "<?php if (isset($_GET[\'ref\'])){echo $_GET[\'ref\'];} ?>"  name="ref" readonly="readonly"/>
<?php
}

那么您只需要使用user_register 钩

add_action(\'user_register\', \'register_refferal\');

function register_refferal($user_id) {
   $userdata = array();
   $userdata[\'ID\'] = $user_id;
   wp_update_user($userdata);
   $userdata[\'ref\'] = $_POST[\'ref\'];

   if (isset($userdata[\'ref\'])  && !empty($userdata[\'ref\']) && $userdata[\'ref\'] != ""){
        //get reffering user id by his login
        $refuser = get_user_by(\'login\',$userdata[\'ref\']);
        //get current refferial credit that user has
        $current_ref_credit = get_user_meta($refuser->ID, \'ref_credit\', true);
        //add credit for the newly created user
        $current_ref_credit[] = $user_id;
        //save the changes
        update_user_meta( $refuser->ID, \'ref_credit\', $current_ref_credit);
   }
}

所以，剩下要做的就是让您的用户共享那里的推荐链接：

http://example.com/wp-login.php?action=register&ref=my_login_name

因此，如果我的用户名是“bainternet”，那么我的推荐链接将是：

http://example.com/wp-login.php?action=register&ref=bainternet

要查看用户下行链路中有多少成员，这里有一个简单的函数，它接受用户ID并返回他引用的用户ID数组：

function get_user_downline($user_id){
    return $current_ref_credit = get_user_meta($user_id, \'ref_credit\', true);
}

其用法很简单：

// to echo count of how many user with ID of 24 as reffered:
echo count(get_user_downline(24));

    // to list the users user with ID of 24 as reffered:
<ul>
<?php
    $reffed = get_users(array(\'orderby\' => \'registered\', \'include\' =>  get_user_downline(24));
    foreach ($blogusers as $user) {
        echo \'<li>\' . $user->display_name . \'</li>\';
    }
?>
</ul>

所以只要复制所有这些代码，就有了一个转诊系统插件