EntityValidator.php

<?php

namespace Redconvive\Bundle\Entity;

use Symfony\Component\Validator\Validator as SymfonyValidator;
use Doctrine\ORM\Event\OnFlushEventArgs;
use Doctrine\ORM\EntityManager;

class Validator 
{
    private $validator;

    function __construct(SymfonyValidator $validator) 
    {
        $this->validator = $validator;
    }

    function onFlush(OnFlushEventArgs $args) 
    {
        foreach ($this->getEntitiesToValidate($args->getEntityManager()) as $entity) {
            $violations = $this->validator->validate($entity);
            if (count($violations)) {
                throw new \Exception("Invalid entity ($violations)");
            }
        }
    }

    private function getEntitiesToValidate(EntityManager $entityManager) 
    {
        return array_merge(
            $entityManager->getUnitOfWork()->getScheduledEntityInsertions(),
            $entityManager->getUnitOfWork()->getScheduledEntityUpdates());
    }
}