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Diffstat (limited to 'framework/caching/dependencies/CDbCacheDependency.php')
| -rw-r--r-- | framework/caching/dependencies/CDbCacheDependency.php | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/framework/caching/dependencies/CDbCacheDependency.php b/framework/caching/dependencies/CDbCacheDependency.php new file mode 100644 index 0000000..98b8e8d --- /dev/null +++ b/framework/caching/dependencies/CDbCacheDependency.php @@ -0,0 +1,112 @@ +<?php +/** + * CDbCacheDependency class file. + * + * @author Qiang Xue <qiang.xue@gmail.com> + * @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 <qiang.xue@gmail.com> + * @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))); + } + } +} |