Compare between old and new data in Symfony 4

It works for me
1. import EntityManager
2. Now you can use this anywhere into the class.

  use Doctrine\ORM\EntityManager;



    $preData = $this->em->getUnitOfWork()->getOriginalEntityData($entity);
    // $preData['active'] for old data and $entity->getActive() for new data
    if($preData['active'] != $entity->getActive()){
        echo 'Send email';
    }