Question

我有2个表，T_PLN和T_PLN_CST_PRD 生成器（M2M.Q_PLN_ID）在数据库（Oracle）中定义，应该用作两个表的主键。

在保存新计划（包含CostPeriod）时，我希望生成器为T_PLN创建一个新的主键，并在T_PLN_CST_PRD中将其用作主键。

表T_PLN PLN_ID //序列生成的主键（长） //更多列

表T_PLN_CST_PRD PLN_ID //主键 - 应与T_PLN表中的相同 //更多列

@Entity
@Table(schema = "M2M", name = "T_PLN")
public class Plan {

    @Id
    @SequenceGenerator(name = "m2mPlanId", sequenceName = "M2M.Q_PLN_ID")
    @GeneratedValue(generator = "m2mPlanId")
    @Column(name = "PLN_ID")
    Long id;

    @OneToOne(cascade = {CascadeType.ALL})
    @JoinColumn(name = "PLN_ID", table = "T_PLN_CST_PRD")
    CostPeriod costPeriod;

    ...   
}



@Entity
@Table(schema = "M2M", name = "T_PLN_CST_PRD")
public class CostPeriod {

    @Id
    @Column(name = "PLN_ID")
    Long planId;

    ...
}

上面的代码缺少连接两个主键的东西，但我不确定是什么......

我尝试了各种各样的关系（@OneToOne with mappedBy，@ JoinColumn，将Plan添加为T_PLN_CST_PRD的成员..）但由于各种原因无法使其工作：

IdentifierGenerationException：在调用save（）之前必须手动分配此类的ID：
IdentifierGenerationException：尝试从null一对一属性中分配id

和其他人......

还尝试了以下解决方案： OneToOne between two tables with shared primary key 没有运气。

如何定义这种关系？

Answer 1

假设JPA 2+，那么您可以轻松地将其映射如下：

@Entity
@Table(schema = "M2M", name = "T_PLN")
public class Plan {

    @Id
    @SequenceGenerator(name = "m2mPlanId", sequenceName = "M2M.Q_PLN_ID")
    @GeneratedValue(generator = "m2mPlanId")
    @Column(name = "PLN_ID")
    Long id;

    @OneToOne(cascade = {CascadeType.ALL}, mappedBy = "plan")
    CostPeriod costPeriod;
}



@Entity
@Table(schema = "M2M", name = "T_PLN_CST_PRD")
public class CostPeriod {

    @Id
    @OneToOne(cascade = {CascadeType.ALL})
    @JoinColumn(name = "PLN_ID")
    Plan plan;
}

确保在保持关系之前设置了关系的两面。

plan.setCostPeriod(costPeriod);
costPeriod.setPlan(plan);

Answer 2

对于双向一对一共享主键模型，我认为您缺少In the finally block of the script. Receiving the output from the job: In the try block of the job. In the finally block of the job.和@PrimaryKeyJoinColumn。

您可以尝试以下映射：

MapsId

保存时：

@Entity
@Table(schema = "M2M", name = "T_PLN")
public class Plan {

    @Id
    @SequenceGenerator(name = "m2mPlanId", sequenceName = "M2M.Q_PLN_ID")
    @GeneratedValue(generator = "m2mPlanId")
    @Column(name = "PLN_ID")
    Long id;

    @OneToOne(cascade = {CascadeType.ALL})
    @PrimaryKeyJoinColumn
    //OR
    //Instead of above @OneToOne and @PrimaryKeyJoinColumn use below:
    //@OneToOne(mappedBy="plan", cascade = {CascadeType.ALL})
    CostPeriod costPeriod;

    ...
}



@Entity
@Table(schema = "M2M", name = "T_PLN_CST_PRD")
public class CostPeriod {

    @Id
    @Column(name = "PLN_ID")
    Long planId;

    @OneToOne
    @JoinColumn(name = "id")
    @MapsId
    private Plan plan;  

    ...
}

Hibernate：如何使用相同的序列生成主键设置两个表之间的关系？

2 个答案: