<?php /** * @link http://www.yiiframework.com/ * @copyright Copyright (c) 2008 Yii Software LLC * @license http://www.yiiframework.com/license/ */ namespace yii\caching; use Yii; use yii\base\InvalidConfigException; use yii\db\Connection; use yii\di\Instance; /** * DbDependency represents a dependency based on the query result of a SQL statement. * * If the query result changes, the dependency is considered as changed. * The query is specified via the [[sql]] property. * * @author Qiang Xue <qiang.xue@gmail.com> * @since 2.0 */ class DbDependency extends Dependency { /** * @var string the application component ID of the DB connection. */ public $db = 'db'; /** * @var string the SQL query whose result is used to determine if the dependency has been changed. * Only the first row of the query result will be used. */ public $sql; /** * @var array the parameters (name => value) to be bound to the SQL statement specified by [[sql]]. */ public $params = []; /** * Generates the data needed to determine if dependency has been changed. * This method returns the value of the global state. * @param Cache $cache the cache component that is currently evaluating this dependency * @return mixed the data needed to determine if dependency has been changed. * @throws InvalidConfigException if [[db]] is not a valid application component ID */ protected function generateDependencyData($cache) { $db = Instance::ensure($this->db, Connection::className()); if ($this->sql === null) { throw new InvalidConfigException("DbDependency::sql must be set."); } if ($db->enableQueryCache) { // temporarily disable and re-enable query caching $db->enableQueryCache = false; $result = $db->createCommand($this->sql, $this->params)->queryOne(); $db->enableQueryCache = true; } else { $result = $db->createCommand($this->sql, $this->params)->queryOne(); } return $result; } }