<?php
/**
 * CExistValidator class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright Copyright &copy; 2008-2009 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CExistValidator validates that the attribute value exists in a table.
 *
 * This validator is often used to verify that a foreign key contains a value
 * that can be found in the foreign table.
 *
 * CExistValidator can only be used for active record objects.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Id$
 * @package system.validators
 * @since 1.0.4
 */
class CExistValidator extends CValidator
{
	/**
	 * @var string the ActiveRecord class name that should be used to
	 * look for the attribute value being validated. Defaults to null,
	 * meaning using the ActiveRecord class of the attribute being validated.
	 * You may use path alias to reference a class name here.
	 * @see attributeName
	 */
	public $className;
	/**
	 * @var string the ActiveRecord class attribute name that should be
	 * used to look for the attribute value being validated. Defaults to null,
	 * meaning using the name of the attribute being validated.
	 * @see className
	 */
	public $attributeName;
	/**
	 * @var boolean whether the attribute value can be null or empty. Defaults to true,
	 * meaning that if the attribute is empty, it is considered valid.
	 */
	public $allowEmpty=true;

	/**
	 * Validates the attribute of the object.
	 * If there is any error, the error message is added to the object.
	 * @param CModel the object being validated
	 * @param string the attribute being validated
	 */
	protected function validateAttribute($object,$attribute)
	{
		$value=$object->$attribute;
		if($this->allowEmpty && ($value===null || $value===''))
			return;

		$className=$this->className===null?get_class($object):Yii::import($this->className);
		$attributeName=$this->attributeName===null?$attribute:$this->attributeName;

		$finder=CActiveRecord::model($className);
		$select=$finder->getTableSchema()->primaryKey;
		$result=$finder->findByAttributes(array($attributeName=>$value),array('select'=>$select));

		if($result===null)
		{
			$message=$this->message!==null?$this->message:Yii::t('yii','{attribute} "{value}" is invalid.');
			$this->addError($object,$attribute,$message,array('{value}'=>$value));
		}
	}
}