Symfony：存储库功能无法获取持久状态

Question

提交具有实体数据的表单后，我想检查某些属性是否已从其数据库状态更改。如果是这样，我需要执行与其没有相同的行动。我写了下面的代码。似乎问题是getRepository()->findOneById()没有从数据库中获取值，而是从某种缓存中获取值。也许Symfony已经考虑在此时更改Dropoffpoint，因此Dropoffpoint->getCommission()的值始终与从getRepository->findOneById()->getCommission()检索到的值相同。

public function editDOPAction(Request $request, DOP $DOP) {
    $form = $this->createForm(DOPType::class, $DOP);
    $deleteForm = $this->createDeleteForm($DOP);
    $form->handleRequest($request);

    if ($form->isSubmitted() && $form->isValid()) {
        $em = $this->getDoctrine()->getManager();
        $existingDOP = $em->getRepository('AppBundle:Dropoffpoint')->findOneById($DOP->getId()); # get DOP with same id
        if ($existingDOP) { # we found one
            if ($existingDOP->getCommission() != $DOP->getCommission()) {
                # commission changed (destructive!)
                $em->remove($existingDOP); #soft-delete the old DOP
                $em->persist($DOP); # persist a new DOP
            } else {
                $em->persist($DOP); # no destructive changes to DOP, just update as usual
            }
            $em->flush();
        }
    }