mysql - Doctrine2 与 Symfony2 : Why does cascade persist not work on this many-to-many relationship?

Question

在我的项目中，我有许多多对多实体。这种多对多关系具有属性，因此我决定将它们分成A 1:n B n:1 C，就像is described in this post .

所以我的简化类结构如下所示。到目前为止一切顺利，但是当我运行 Controller (也在下面列出)插入值时出现异常:

An exception occurred while executing 'INSERT INTO b (...) VALUES (...)' with params {...}

SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'class_a_id' cannot be null

我做错了什么？

A类

<?
/**
 * @ORM\Entity
 * @ORM\Table(name="a")
 */
class ClassA {
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     **/
    protected $id;

    /** OTHER FIELDS **/

    /**
     * @ORM\OneToMany(targetEntity="ClassB", mappedBy="class_a", cascade={"persist", "remove"})
     **/
    protected $class_b;
}

B 类

/**
 * @ORM\Entity
 * @ORM\Table(name="b")
 */
class ClassB {
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     **/
    protected $id;
    /**
     * @ORM\ManyToOne(targetEntity="ClassC", inversedBy="class_b")
     * @ORM\JoinColumn(name="class_c_id", referencedColumnName="id", nullable=false)
     **/
    protected $class_c;
    /**
     * @ORM\ManyToOne(targetEntity="ClassA", inversedBy="class_b")
     * @ORM\JoinColumn(name="class_a_id", referencedColumnName="id", nullable=false)
     **/
     protected $class_a;

    /** OTHER FIELDS **/
}

C 类

/**
 * @ORM\Entity
 * @ORM\Table(name="c")
 */
class ClassC {
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /** OTHER FIELDS **/

    /**
     * @ORM\OneToMany(targetEntity="ClassB", mappedBy="class_c")
     **/
    protected $class_b;
}

Controller

$em = $this->getDoctrine()->getEntityManager();
$a = new ClassA();
$a->setXXX() //Setting some other fields
foreach(...) {
    $b = new ClassB();
    $b->setClass_C(...); //found by doctrine out of database and set into classB
    $b->setXXX() //Setting some other fields
    $a->addClass-B($b); //added ClassB into ClassA
}
$em->persist($a);
$em->flush();

Answer 1

感谢您考虑我的问题，但已经解决了!只需将类 a 添加到 b 中即可轻松解决该问题。所以我的 Controller 现在可以工作了。请参阅下面的差异:

Controller

$em = $this->getDoctrine()->getEntityManager();
$a = new ClassA();
$a->setXXX() //Setting some other fields
foreach(...) {
    $b = new ClassB();
    $b->setClass_C(...); //found by doctrine out of database and set into classB
    $b->setXXX() //Setting some other fields
    $a->addClass-B($b); //added ClassB into ClassA
    $b->setClass_A($a); //add ClassA into Class B !!NEW!!
}
$em->persist($a);
$em->flush();