JPA @ManyToMany具有公共连接列

Question

我有以下三个表：

测验

• quiz_id

问题

• quiz_id
• question_id

答案

• quiz_id
• answer_id

questions_answers

• quiz_id
• question_id
• answer_id

问题有一个由quiz_id和question_id组成的复合PK。答案还有一个由quiz_id和answer_id组成的复合PK。

每个测验都有自己的问题和答案，这些问题和答案在多对多关系中（在测验的范围内）相互匹配。我知道这听起来有点奇怪，但问题可能有几个答案，一个答案也可能与不同的问题有关。

我正在尝试在QuestionEntity中实现这种关系。这是我班级的相关部分：

@Entity
@Table(name = "questions")
public class QuestionEntity implements Serializable {

    @EmbeddedId
    private QuestionPK primaryKey = new QuestionPK();

    @ManyToMany
    @JoinTable(
            name = "questions_answers",
            joinColumns = {
                    @JoinColumn(name = "quiz_id", referencedColumnName = "quiz_id"),
                    @JoinColumn(name = "question_id", referencedColumnName = "question_id")
            },
            inverseJoinColumns = {
                    @JoinColumn(name = "quiz_id", referencedColumnName = "quiz_id"),
                    @JoinColumn(name = "answer_id", referencedColumnName = "answer_id")
            }
    )
    private List<AnswerEntity> keys = new ArrayList<AnswerEntity>();
}

我在编译时遇到以下错误：

Caused by: org.hibernate.MappingException: Repeated column in mapping for collection: ru.andrewquiz.dao.quiz.QuestionEntity.keys column: quiz_id

这是否意味着我必须在我的questions_answers表中创建2个单独的列：question_quiz_id和answer_quiz_id？虽然在我的例子中，它们总是包含对同一个测验的引用？

修改 我查看了@XtremeBaumer建议的示例：link。试图实现它，引入QuestionsAnswersEntity.class并根据示例更改其他类。我的QuestionsAnswersEntity类声明如下：

@Entity
@Table(name = "questions_answers")
@AssociationOverrides({
        @AssociationOverride(name = "primaryKey.question",
            joinColumns = {@JoinColumn(name = "quiz_id", referencedColumnName = "quiz_id"),
                @JoinColumn(name = "question_id", referencedColumnName = "question_id")}),
        @AssociationOverride(name = "primaryKey.answer",
            joinColumns = {@JoinColumn(name = "quiz_id", referencedColumnName = "quiz_id"),
                @JoinColumn(name = "answer_id", referencedColumnName = "answer_id")})
})
public class QuestionsAnswers implements Serializable {...}

然而，这似乎对我的问题没有多大影响，因为hibernate再次抱怨我的quiz_id列是两个不同表的外键的一部分。我得到了和以前一样的错误。