DbDependency.php 2.4 KB
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<?php
/**
 * @link http://www.yiiframework.com/
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 * @copyright Copyright (c) 2008 Yii Software LLC
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 * @license http://www.yiiframework.com/license/
 */

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namespace yii\caching;

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use Yii;
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use yii\base\InvalidConfigException;
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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>
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 * @since 2.0
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 */
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class DbDependency extends Dependency
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{
	/**
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	 * @var string the application component ID of the DB connection.
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	 */
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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.
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	 * 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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	 */
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	public $params;
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	/**
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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]].
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	 * @param array $config name-value pairs that will be used to initialize the object properties
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	 */
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	public function __construct($sql, $params = array(), $config = array())
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	{
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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.
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	 * @param Cache $cache the cache component that is currently evaluating this dependency
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	 * @return mixed the data needed to determine if dependency has been changed.
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	 * @throws InvalidConfigException if [[db]] is not a valid application component ID
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	 */
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	protected function generateDependencyData($cache)
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	{
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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.");
		}

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		if ($db->enableQueryCache) {
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			// temporarily disable and re-enable query caching
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			$db->enableQueryCache = false;
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			$result = $db->createCommand($this->sql, $this->params)->queryOne();
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			$db->enableQueryCache = true;
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		} else {
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			$result = $db->createCommand($this->sql, $this->params)->queryOne();
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		}
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		return $result;
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	}
}