两个属性与一个实体Symfony2共享相同的OneToMany关系

Question

我们先来描述一下我的情况.我正在使用Symfony2,我的实体之间的关系有问题.

我有两个链接在一起的实体.这两个实体是AssociationQuestion和AssociationPossibleAnswer.我目前正在创建一个问题软件,其中必须将左侧的一个可能答案与右侧的另一个可能答案相关联,例如在以下示例中:

目前,我正计划在类中使用两个属性来AssociationQuestion保存许多AssociationPossibleAnswer对象.第一个数组将包含左侧可能的答案,第二个数组将包含右侧可能的答案.

因此,对我来说,看起来我将有两个oneToMany关系 AssociationQuestion

AssociationQuestion:

    oneToMany:
        possibleAnswersLeft:
            targetEntity: AssociationPossibleAnswer
            mappedBy: associationQuestion

        possibleAnswersRight:
            targetEntity: AssociationPossibleAnswer
            mappedBy: associationQuestion

然后,在AssociationPossibleAnswer,我会有一个ManyToOne关系:

AssociationPossibleAnswer:
    manyToOne:
        associationQuestion:
            targetEntity: AssociationQuestion

问题是我在尝试验证我的学说时遇到以下错误.似乎你不能像我希望的那样将两个实体链接到一个......

* The field AssociationQuestion#possibleAnswersLeft is on the inverse side of a bi-directional relationship, but the specified mappedBy association on the target-entity AssociationPossibleAnswer#associationQuestion does not contain the required 'inversedBy=possibleAnswersLeft' attribute.

* The field AssociationQuestion#possibleAnswersRight is on the inverse side of a bi-directional relationship, but the specified mappedBy association on the target-entity AssociationPossibleAnswer#associationQuestion does not contain the required 'inversedBy=possibleAnswersRight' attribute.

我想知道这是否是在我的两个实体之间建立关系的正确方法.是否有可能有两个属性指向实体,而实体却不知道它指向哪个属性.

Answer 1

使用OneToMany关联无法解决此案例.

你需要之间的2个不同的关系AssociationQuestion和AssociationPossibleAnswer.你设置它的方式,你只有1个关系.只需看看您创建的1 ManyToOne关联AssociationPossibleAnswer.

并且你试图在这个关系中有两个相反的方面,这在理论上是不可能的.关系只能有2个端点(不是3个).

解

实现2(单向)ManyToMany关联AssociationQuestion,并使外键指向AssociationPossibleAnswer唯一:

class AssociationQuestion
{

    /**
     * @ORM\ManyToMany(targetEntity="AssociationPossibleAnswer")
     * @ORM\JoinTable(name="association_question_association_possible_answer_left",
     *     joinColumns={@ORM\JoinColumn(name="association_question_id", referencedColumnName="id")},
     *     inverseJoinColumns={@ORM\JoinColumn(name="association_possible_answer_id", referencedColumnName="id", unique=true)}
     * )
     */
    private $possibleAnswersLeft;

    /**
     * @ORM\ManyToMany(targetEntity="AssociationPossibleAnswer")
     * @ORM\JoinTable(name="association_question_association_possible_answer_right",
     *     joinColumns={@ORM\JoinColumn(name="association_question_id", referencedColumnName="id")},
     *     inverseJoinColumns={@ORM\JoinColumn(name="association_possible_answer_id", referencedColumnName="id", unique=true)}
     * )
     */
    private $possibleAnswersRight;

    // ...

Doctrine称这是一对多,单向与联接表关联.