在Symfony中使用JSON反序列化实体失败

Question

I'm trying to deserialize an entity from a JSON file with this method

public function importAnnotationAction($id_rendu)
{
    $em = $this->getDoctrine()->getEntityManager();

    $jsonContent = $this->get("request")->getContent();

    $serializer = $this->get('serializer');
    $annotationEntity = $serializer->deserialize($jsonContent, 'Alecsia\AnnotationBundle\Entity\Annotation', 'json');

    //Save entity
    $em->persist($annotationEntity);
    $em->flush();

    return new Response($jsonContent . "
" . var_dump($annotationEntity));
}

the JSON file used is from a same entity

and the output entity fields are all set to null :

object(Alecsia\AnnotationBundle\Entity\Annotation)#568 (18) { ["id":protected]=> int(26) ["fichier":protected]=> NULL ["rendu":protected]=> NULL ["modele":protected]=> NULL ["debut_ligne":protected]=> int(0) ["debut_col":protected]=> int(0) ["fin_ligne":protected]=> int(0) ["fin_col":protected]=> int(0) ["nom":protected]=> NULL ["commentaire":protected]=> NULL ["valeur":protected]=> NULL ["relatif":protected]=> NULL ["exercice":protected]=> NULL ["deleguer_nom":protected]=> bool(false) ["deleguer_commentaire":protected]=> bool(false) ["deleguer_valeur":protected]=> bool(false) ["deleguer_relatif":protected]=> bool(false) ["deleguer_exercice":protected]=> bool(false) }

and the entity id increment with each call, what am I doind wrong?