Question

假设我有以下SQL表定义：

create table overview (
   key          bigserial not null,
   supplemental decimal(20) not null,
   constraint overview_pk primary key (key)
);
create table details (
   key        decimal(20) not null,
   ver        decimal(20) not null,
   constraint details_pk primary key (key, ver)
);

此外，我有两个适当的JPA映射类，如下所示：

@Entity
@Table(name = "overview")
public class Overview implements Serializable {
  private static final long serialVersionUID = 1L;

  @Id
  @GeneratedValue(strategy = GenerationType.SEQUENCE)
  @Column(name = "key", unique = true, nullable = false)
  private BigDecimal key;

  @Column(nullable = false)
  private BigDecimal supplemental;

  @OneToOne(mappedBy = "overview")
  private Details details;

  public Overview() {
  }

  public Overview(BigDecimal supplemental, Details details) {
    this.details = details;
    this.details.setOverview(this);
  }

@Entity
@Table(name = "details")
public class Details implements Serializable {
  private static final long serialVersionUID = 1L;

  @Id
  @Column(name = "key", nullable = false)
  protected BigDecimal key;

  @Column(name = "ver", nullable = false)
  protected BigDecimal ver;

  @OneToOne(fetch = FetchType.LAZY)
  @MapsId(value = "key")
  private Overview overview;

  public Details() {
  }

  public Overview getOverview() {
    return overview;
  }

  public void setOverview(Overview overview) {
    this.overview = overview;
  }


}

目的是在表overview中生成单个密钥，并将该密钥用于两个方面。首先是details表中的外键，也是overview表的主键。

一个问题是：Hibernate / Spring Data JPA可以实现吗？ Based on what I have read it should be?

我有一些测试代码可以将内容保存到overview，details表中，但总是失败并显示如下错误消息：

nested exception is java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: 
object references an unsaved transient instance - save the transient instance before flushing 
: xyz.modell.Overview.details 
-> xyz.modell.Details

也许有人知道我做错了什么？

使用一个表的主键作为另一个表的外键

0 个答案: