如何解决级联在继承中不起作用

Question

persist方法在继承类中不起作用，尽管我已在批注（cascade =“ all”）中设置了级联属性。

/**
 * @ORM\Entity
 * @ORM\InheritanceType("JOINED")
 * @ORM\DiscriminatorColumn(name="tipo", type="string")
 * @ORM\DiscriminatorMap({"menu" = "Menu", "enquete" = "Enquete"})
 */
 abstract class Widget{

   /**
    * @ORM\Id
    */
    protected $id;

 }
 /**
  * @ORM\Entity
  */
 class Enquete extends Widget{   

    /**
     * @var ArrayCollection
     * @ORM\OneToMany(targetEntity="Admin\Model\Alternativa", mappedBy="enquete", cascade="all")
     */
     protected $alternativas;
 }

 /**
  * @ORM\Entity
  */
 class Alternativa{       
    /**
     * @ORM\ManyToOne(targetEntity="Admin\Model\Enquete", inversedBy="alternativas")
     * @ORM\joinColumn(name="Enquete_id", referencedColumnName="id")
     */
     protected $enquete;

}

我在级联中使用持久性，但不起作用： $enquete->addAlternativa(New Alternativa()); $entityManager->persist($enquete); $entityManager->flush();

结果是跟随错误： SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'Enquete_id' cannot be null