Formal\Form::validateUnique PHP Method

    function validateUnique($sValue, \Formal\Form\Morphology $oMorpho, \Formal\Element $oElement)
    {
        $oModelInstance = $this->modelInstance();
        $oRequest = $oModelInstance->getBaseRequester()->addClauseEquals($oElement->option("prop"), $sValue);
        if (!$oModelInstance->floating()) {
            # checking id only if model instance is not floating
            $oRequest->addClauseNotEquals($oModelInstance::PRIMARYKEY, $oModelInstance->get($oModelInstance::PRIMARYKEY));
        }
        $oColl = $oRequest->execute();
        if ($oColl->count() > 0) {
            return "<strong>" . $oElement->option("label") . "</strong> has to be unique. Given value is not available.";
        }
        return true;
    }