Since 184.108.40.20697 version of CakePHP, the function
DataSource::getFieldValue() has been disappeared :), but a reference is remained in the
Starting from a post on the mailing list, if you get an error like Fatal error: Call to undefined function: getfieldvalue() in …\cake\libs\controller\components\dbacl\models\aclnode.php on line 113, you can easily fix it by changing the line (aclnode.php:113) from
$idList = DataSource::getFieldValue(...
$idList = Set::extract(...