1: <?php
  2: /**
  3:  * CDbCacheDependency class file.
  4:  *
  5:  * @author Qiang Xue <qiang.xue@gmail.com>
  6:  * @link http://www.yiiframework.com/
  7:  * @copyright 2008-2013 Yii Software LLC
  8:  * @license http://www.yiiframework.com/license/
  9:  */
 10: 
 11: /**
 12:  * CDbCacheDependency represents a dependency based on the query result of a SQL statement.
 13:  *
 14:  * If the query result (a scalar) changes, the dependency is considered as changed.
 15:  * To specify the SQL statement, set {@link sql} property.
 16:  * The {@link connectionID} property specifies the ID of a {@link CDbConnection} application
 17:  * component. It is this DB connection that is used to perform the query.
 18:  *
 19:  * @author Qiang Xue <qiang.xue@gmail.com>
 20:  * @package system.caching.dependencies
 21:  * @since 1.0
 22:  */
 23: class CDbCacheDependency extends CCacheDependency
 24: {
 25:     /**
 26:      * @var string the ID of a {@link CDbConnection} application component. Defaults to 'db'.
 27:      */
 28:     public $connectionID='db';
 29:     /**
 30:      * @var string the SQL statement whose result is used to determine if the dependency has been changed.
 31:      * Note, the SQL statement should return back a single value.
 32:      */
 33:     public $sql;
 34:     /**
 35:      * @var array parameters (name=>value) to be bound to the SQL statement specified by {@link sql}.
 36:      * @since 1.1.4
 37:      */
 38:     public $params;
 39: 
 40:     private $_db;
 41: 
 42:     /**
 43:      * Constructor.
 44:      * @param string $sql the SQL statement whose result is used to determine if the dependency has been changed.
 45:      */
 46:     public function __construct($sql=null)
 47:     {
 48:         $this->sql=$sql;
 49:     }
 50: 
 51:     /**
 52:      * PHP sleep magic method.
 53:      * This method ensures that the database instance is set null because it contains resource handles.
 54:      * @return array
 55:      */
 56:     public function __sleep()
 57:     {
 58:         $this->_db=null;
 59:         return array_keys((array)$this);
 60:     }
 61: 
 62:     /**
 63:      * Generates the data needed to determine if dependency has been changed.
 64:      * This method returns the value of the global state.
 65:      * @throws CException if {@link sql} is empty
 66:      * @return mixed the data needed to determine if dependency has been changed.
 67:      */
 68:     protected function generateDependentData()
 69:     {
 70:         if($this->sql!==null)
 71:         {
 72:             $db=$this->getDbConnection();
 73:             $command=$db->createCommand($this->sql);
 74:             if(is_array($this->params))
 75:             {
 76:                 foreach($this->params as $name=>$value)
 77:                     $command->bindValue($name,$value);
 78:             }
 79:             if($db->queryCachingDuration>0)
 80:             {
 81:                 // temporarily disable and re-enable query caching
 82:                 $duration=$db->queryCachingDuration;
 83:                 $db->queryCachingDuration=0;
 84:                 $result=$command->queryRow();
 85:                 $db->queryCachingDuration=$duration;
 86:             }
 87:             else
 88:                 $result=$command->queryRow();
 89:             return $result;
 90:         }
 91:         else
 92:             throw new CException(Yii::t('yii','CDbCacheDependency.sql cannot be empty.'));
 93:     }
 94: 
 95:     /**
 96:      * @return CDbConnection the DB connection instance
 97:      * @throws CException if {@link connectionID} does not point to a valid application component.
 98:      */
 99:     protected function getDbConnection()
100:     {
101:         if($this->_db!==null)
102:             return $this->_db;
103:         else
104:         {
105:             if(($this->_db=Yii::app()->getComponent($this->connectionID)) instanceof CDbConnection)
106:                 return $this->_db;
107:             else
108:                 throw new CException(Yii::t('yii','CDbCacheDependency.connectionID "{id}" is invalid. Please make sure it refers to the ID of a CDbConnection application component.',
109:                     array('{id}'=>$this->connectionID)));
110:         }
111:     }
112: }
113: