public function isUniqueValue($strField, $varNew, $intId = null)
    {
        $attribute = $this->getMetaModel()->getAttribute($strField);
        if ($attribute) {
            $matchingIds = $this
                ->prepareFilter(
                    $this->getEmptyConfig()->setFilter(
                        array(
                            array(
                                'operation' => '=',
                                'property' => $attribute->getColName(),
                                'value' => $varNew
                            )
                        )
                    )
                )
                ->getMatchingIds();
            return (count($matchingIds) == 0) || ($matchingIds == array($intId));
        }

        return false;
    }