数据映射器ORM/代码点火器--验证关系

我有以下数据库：

CREATE TABLE users
(
id BIGINT NOT NULL AUTO_INCREMENT,
PRIMARY KEY (id)
);
CREATE TABLE likes
(
id BIGINT NOT NULL AUTO_INCREMENT,
user_id BIGINT,
idea_id BIGINT,
PRIMARY KEY (id)
);
CREATE TABLE ideas
(
id BIGINT NOT NULL AUTO_INCREMENT,
PRIMARY KEY (id)
);

用户模型：

// --------------------------------------------------------------------
// Relationships
// --------------------------------------------------------------------
public $has_many = array( 'like' , 'idea' , 'comment' );
// --------------------------------------------------------------------
// Validation
// --------------------------------------------------------------------
var $validation = array(
    'username' => array(
        'label' => 'Username',
        'rules' => array('required', 'trim', 'unique', 'min_length' => 3 )
    ),
    'password' => array(
        'label' => 'Password',
        'rules' => array('required', 'trim', 'min_length' => 3 ,'encrypt' )
    )
);

想法模型：

public $has_one = array('user');
public $has_many = array('like');
// --------------------------------------------------------------------
// Validation
// --------------------------------------------------------------------
public $validation = array(
    'user' => array(
        'rules' => array('required')
    )
);

类似型号：

// Relationships
// --------------------------------------------------------------------
public $has_one = array( 'user' , 'idea' );
// --------------------------------------------------------------------
// Validation
// --------------------------------------------------------------------
var $validation = array(
    'user' => array(
        'rules' => array('required', 'unique_pair' => 'idea' )
    ),
    'idea' => array(
        'rules' => array('required')
    )
);

类似控制器

    $idea = new Idea(1);
    $user = new User(1);
    $like = new Like(); 
    if( !$like->save( array( $idea , $user ) ) )
    {
          echo $like->error->all;
    }
    else
    {
      echo "ok";    
    }   

问题是，我总是觉得不错，点赞被保存在数据库中，没有得到验证。

我想要的是获得两个字段（user_id，idea_id）唯一的