Problème avec ManyTOOne

Bonjour ,

j'ai un problème avec la relation ManyToOne ,
j'ai fais modification sur 3 tables mais lorsque je veux persister que la modification de deux tables seulement cette erreur surgit

Citation:

A new entity was found through the relationship 'AppBundle\Entity\Language_Bear#language' that was not configured to cascade persist operations for entity: c. To solve this issue: Either explicitly call EntityManager#persist() on this unknown entity or configure cascade persist this association in the mapping for example @ManyToOne(..,cascade={"persist"}).

voici mon code

Code:

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  $bear = new Bear;
        $language=new Language();
        $lang_bear=new Language_Bear();
        $lang = $this->getDoctrine()
            ->getRepository('AppBundle:Language')
            ->findAll();
        $form = $this->createForm(BearType::class, $bear,['lang'=>$lang]);
 
        $form->handleRequest($request);
        if ($form->isSubmitted() && $form->isValid()) {
 
            $nom = $form['NomBear']->getData();
         $a=$form->get('Language')->getData();
         $b="".$a[0];
            $option = $form['Option']->getData();
            $bear->setNomBear($nom);
            $lang_bear->setOption($option);
            $language->setNomLanguage($b);
            $language->setFilter("");
            $lang_bear->setBear($bear);
            $lang_bear->setLanguage($language);
            $em=$this->getDoctrine()->getManager();
            $em->persist($bear);
            $em->persist($lang_bear);
            $em->flush();}

Que dois je faire pour remédier à ce problème?
Merci.