/**
* 检查用户名是否存在(该方法非响应资源型方法)
*
* @param string $username 用户名
* @return bool 若用户名存在则返回true, 否者为false
*/
public function getUsernameExists($username)
{
$this->validation->validate('username', $username);
$user = Users::findFirst(array('conditions' => 'username = ?0', 'bind' => array($username)));
return (bool) $user;
}
