private function setupRelations()
{
$className = get_class($this);
if (!isset(self::$_relations[$className])) {
$class = new ReflectionClass($className);
$relations = array();
foreach ($class->getStaticPropertyValue('RELATIONS') as $key => $value) {
$relations[strtolower($key)] = array($key, $value);
}
self::$_relations[$className] = $relations;
}
}