public function findByAttributeIdAndProductId($attributeId, $productId)
    {
        try {
            $queryBuilder = $this->createQueryBuilder('productAttribute')
                ->leftJoin('productAttribute.attribute', 'attribute')
                ->leftJoin('productAttribute.product', 'product')
                ->andWhere('attribute.id = :attributeId')
                ->andWhere('product.id = :productId')
                ->setParameter('attributeId', $attributeId)
                ->setParameter('productId', $productId);

            return $queryBuilder->getQuery()->getSingleResult();
        } catch (NoResultException $exc) {
            return null;
        }
    }