JPA。 Stackoverflow级联合并 [英] JPA. Stackoverflow on cascade merge

问题描述

这是我的JPA结构：

电影（查看级联类型）：

Movie (look at cascade types):

@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;
}

当我调用 entityManager.merge（Movie movie） 与 CascadeType.ALL 我得到StackOverflowError。如果删除级联，合并调用不会抛出错误。哪里可能有问题？

When I call entityManager.merge(Movie movie) with CascadeType.ALL I get the StackOverflowError. If remove cascading, merge call doesn't throw the error. Where may be a problem?

堆栈跟踪：
http://paste.ofcode.org/YHMTG5QesmgWdfFAA6RAaZ

我认为这个问题与复合主键有关。 merge 在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。

I think this problem related to composite primary key. There is no error when merge performed on another entities with the same one-to-many relationship, but without composite id.

推荐答案

StackOverflow是由循环关系造成的。为避免出现异常，我在多对多表中标记为 @ManyToOne（fetch = FetchType.LAZY）。

StackOverflow was caused by cyclic relations. To avoid exception I marked keys in many-to-many table as @ManyToOne(fetch = FetchType.LAZY).

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

That's how my tables look after modifications: https://stackoverflow.com/a/32544519/2089491

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