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