JPA。级联合并上的 Stackoverflow

Question

这是我的 JPA 结构：

电影（看看级联类型）：

@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;
    .....
}

评级 ID：

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

    @ManyToOne
    private User user;
}

当我打电话时entityManager.merge(Movie movie)，CascadeType.ALL我收到 StackOverflowError。如果删除级联，合并调用不会抛出错误。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。为了避免异常，我将多对多表中的键标记为@ManyToOne(fetch = FetchType.LAZY).

这就是我的表格在修改后的样子：https : //stackoverflow.com/a/32544519/2089491