[英]Hibernate: how to delete entities in many-to-many relationships with extra attributes
我有以下關系:
@OneToMany(fetch = FetchType.EAGER, mappedBy="note", cascade = CascadeType.REMOVE, orphanRemoval = true)
private Set<Review> reviews = new HashSet<>();
在Note.java和
@OneToMany(fetch = FetchType.EAGER, mappedBy = "expert", cascade = CascadeType.ALL, orphanRemoval = true)
private Set<Review> notes = new HashSet<>();
在Expert.java 中。
如您所見,它們指的是 Review 類,它表示 Note 和 Expert 之間的 M 到 N 關系。 由於我需要為此關系添加額外的屬性,因此我創建了一個 ReviewId 類和一個 Review 類,如下所示:
@Embeddable
public class ReviewId implements Serializable {
@Column(name = "fk_note")
protected Long noteId;
@Column(name = "fk_expert")
protected Long expertId;
[...]
}
@Entity
public class Review {
@EmbeddedId
private ReviewId id;
private int value;
private String comment;
@ManyToOne
@JoinColumn(name = "fk_note", insertable = false, updatable = false)
private Note note;
@ManyToOne
@JoinColumn(name = "fk_expert", insertable = false, updatable = false)
private Expert expert;
[...]
}
當我嘗試刪除出現在此關系中的注釋或專家時,出現以下錯誤:
Cannot delete or update a parent row: a foreign key constraint fails (`db_example`.`review`, CONSTRAINT `FKls65s9wl28v98ts2kifir37p7` FOREIGN KEY (`fk_note`) REFERENCES `note` (`id`))
當我刪除某個注釋/專家時,如何讓 Hibernate 刪除與它們相關的所有評論? 謝謝!
這可以通過FluentJPA完成:
long noteId; //passed as a parameter
FluentQuery query = FluentJPA.SQL((Review review) -> {
DELETE().FROM(review);
WHERE(review.getId().getNoteId() == noteId);
});
...
query.createQuery(em).executeUpdate();
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