/**
* Initializes the DbMessageSource component.
* This method will initialize the [[db]] property to make sure it refers to a valid DB connection.
* Configured [[cache]] component would also be initialized.
* @throws InvalidConfigException if [[db]] is invalid or [[cache]] is invalid.
*/
public function init()
{
parent::init();
$this->db = Instance::ensure($this->db, Connection::className());
if ($this->enableCaching) {
$this->cache = Instance::ensure($this->cache, Cache::className());
}
}