Yii2 Bootstrap 3
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<?php
/**
* DbDependency class file.
*
* @link http://www.yiiframework.com/
* @copyright Copyright &copy; 2008-2012 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
namespace yii\caching;
use yii\base\Exception;
use yii\db\Connection;
use yii\db\Query;
/**
* 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 [[query]] property.
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @since 2.0
*/
class DbDependency extends Dependency
{
/**
* @var string the ID of the [[Connection|DB connection]] application component. Defaults to 'db'.
*/
public $connectionID = 'db';
/**
* @var Query 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 $query;
/**
* @var Connection the DB connection instance
*/
private $_db;
/**
* Constructor.
* @param Query $query the SQL query whose result is used to determine if the dependency has been changed.
* @param array $config name-value pairs that will be used to initialize the object properties
*/
public function __construct($query = null, $config = array())
{
$this->query = $query;
parent::__construct($config);
}
/**
* 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 generateDependencyData()
{
$db = $this->getDbConnection();
$command = $this->query->createCommand($db);
if ($db->enableQueryCache) {
// temporarily disable and re-enable query caching
$db->enableQueryCache = false;
$result = $command->queryRow();
$db->enableQueryCache = true;
} else {
$result = $command->queryRow();
}
return $result;
}
/**
* Returns the DB connection instance used for caching purpose.
* @return Connection the DB connection instance
* @throws Exception if [[connectionID]] does not point to a valid application component.
*/
public function getDbConnection()
{
if ($this->_db === null) {
$db = \Yii::$application->getComponent($this->connectionID);
if ($db instanceof Connection) {
$this->_db = $db;
} else {
throw new Exception("DbDependency.connectionID must refer to the ID of a DB connection application component.");
}
}
return $this->_db;
}
/**
* Sets the DB connection used by the cache component.
* @param Connection $value the DB connection instance
*/
public function setDbConnection($value)
{
$this->_db = $value;
}
}