JPA。级联合并时的Stackoverflow

Question

这是我的JPA结构：

电影（看级联类型）：

@Entity
@Table(name = "movie")
public class Movie {

    @Id
    @Column(name = "movie_id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    //@OneToMany(cascade = CascadeType.ALL, mappedBy = "primaryKey.movie") //stack overflow
    @OneToMany(mappedBy = "primaryKey.movie") //works fine
    private List<Rating> ratings;
    ....
}

评分：

@Entity
@Table(name = "rating")
@AssociationOverrides({@AssociationOverride(name = "primaryKey.movie", joinColumns = @JoinColumn(name = "movie_id")),
        @AssociationOverride(name = "primaryKey.user", joinColumns = @JoinColumn(name = "imdb_user_id"))})
public class Rating {
    @EmbeddedId
    private RatingId primaryKey = new RatingId();

    @Column(name = "rating_value")
    private Integer ratingValue;
    .....
}

RatingId：

@Embeddable
public class RatingId implements Serializable{
    @ManyToOne
    private Movie movie;

    @ManyToOne
    private User user;
}

当我致电时entityManager.merge(Moviemovie)，CascadeType.ALL我得到了。如果删除级联，则合并调用不会引发错误。哪里可能有问题？

我认为这个问题与复合主键有关。在merge具有相同一对多关系但没有复合ID的另一个实体上执行时没有错误。

Answer 1

StackOverflow是由循环关系引起的。为了避免出现异常，我在多对多表中将键标记为@ManyToOne(fetch =FetchType.LAZY)。