Three table association on Cakephp

Post.php

<?php
class Post extends AppModel {
  var $hasOne = 'PostUser';
}

PostsController.php

<?php
class PostsController extends AppController {
  var $uses = array('Post', 'User', 'PostUser');

  function index() {
    $this->data = $this->PostUser->find();
    pr($this->data);
  }
}

/* pr dump

Array
(
    [PostUser] => Array
        (
            [id] => 1
            [post_id] => 1
            [user_id] => 1
            [hoge] => 1 - 1
        )

    [Post] => Array
        (
            [id] => 1
            [title] => test title
        )

    [User] => Array
        (
            [id] => 1
            [name] => test name
        )

)
*/

PostUser.php

<?php
class PostUser extends AppModel {
  var $belongsTo = array('Post', 'User');
  var $virtualFields = array(
    'hoge' => "CONCAT('Post.id', ' - ', 'User.id')" // or "CONCAT(Post.title, ' - ', User.name)"
  );
}

User.php

<?php
class User extends AppModel {
  var $hasOne = 'PostUser';
}