File size: 3.25Kb
<?php
/**
* CDbCacheDependency class file.
*
* @author Qiang Xue <[email protected]>
* @link http://www.yiiframework.com/
* @copyright Copyright © 2008-2011 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
/**
* CDbCacheDependency represents a dependency based on the query result of a SQL statement.
*
* If the query result (a scalar) changes, the dependency is considered as changed.
* To specify the SQL statement, set {@link sql} property.
* The {@link connectionID} property specifies the ID of a {@link CDbConnection} application
* component. It is this DB connection that is used to perform the query.
*
* @author Qiang Xue <[email protected]>
* @version $Id: CDbCacheDependency.php 3204 2011-05-05 21:36:32Z alexander.makarow $
* @package system.caching.dependencies
* @since 1.0
*/
class CDbCacheDependency extends CCacheDependency
{
/**
* @var string the ID of a {@link CDbConnection} application component. Defaults to 'db'.
*/
public $connectionID='db';
/**
* @var string the SQL statement whose result is used to determine if the dependency has been changed.
* Note, the SQL statement should return back a single value.
*/
public $sql;
/**
* @var array parameters (name=>value) to be bound to the SQL statement specified by {@link sql}.
* @since 1.1.4
*/
public $params;
private $_db;
/**
* Constructor.
* @param string $sql the SQL statement whose result is used to determine if the dependency has been changed.
*/
public function __construct($sql=null)
{
$this->sql=$sql;
}
/**
* PHP sleep magic method.
* This method ensures that the database instance is set null because it contains resource handles.
* @return array
*/
public function __sleep()
{
$this->_db=null;
return array_keys((array)$this);
}
/**
* Generates the data needed to determine if dependency has been changed.
* This method returns the value of the global state.
* @return mixed the data needed to determine if dependency has been changed.
*/
protected function generateDependentData()
{
if($this->sql!==null)
{
$db=$this->getDbConnection();
$command=$db->createCommand($this->sql);
if(is_array($this->params))
{
foreach($this->params as $name=>$value)
$command->bindValue($name,$value);
}
if($db->queryCachingDuration>0)
{
// temporarily disable and re-enable query caching
$duration=$db->queryCachingDuration;
$db->queryCachingDuration=0;
$result=$command->queryRow();
$db->queryCachingDuration=$duration;
}
else
$result=$command->queryRow();
return $result;
}
else
throw new CException(Yii::t('yii','CDbCacheDependency.sql cannot be empty.'));
}
/**
* @return CDbConnection the DB connection instance
* @throws CException if {@link connectionID} does not point to a valid application component.
*/
protected function getDbConnection()
{
if($this->_db!==null)
return $this->_db;
else
{
if(($this->_db=Yii::app()->getComponent($this->connectionID)) instanceof CDbConnection)
return $this->_db;
else
throw new CException(Yii::t('yii','CDbCacheDependency.connectionID "{id}" is invalid. Please make sure it refers to the ID of a CDbConnection application component.',
array('{id}'=>$this->connectionID)));
}
}
}