Hibernate OneToOne mapping to different tables

Question

I need to persist a data structure that has value which is either a string, double or date.

Is there a way to do a one-to-one mapping, conditional by table?

I tried this...

 implicit def CallHandlerAsResult[R : Defaultable]: AsResult[CallHandler[R]] = new AsResult {
    def asResult(c: =>CallHandler[R]) = {
      c
      Success
    }
 }

However, hibernate doesn't like this:

Caused by: org.hibernate.MappingException: Repeated column in mapping for entity:

Is there a way to configure hibernate to handle this? Or should I simply re-model the FIELD_CRITERIA table to include 3 optional OneToMany relationships?

Answer 1

First you may try to make DateCriteriaEntity and NumericCriteriaEntity the owners of the "one-to-one" relation, not the FieldCriteriaEntity. Move the CRITERIA_ID column to tables that correspond to NumericCriteriaEntity and DateCriteriaEntity so that the column will store FieldCriteriaEntity id as foreign key, and use @OneToMany(mappedBy="correspondent field name") in FieldCriteriaEntity instead of your variant.

Consider this article http://uaihebert.com/jpa-onetoone-unidirectional-and-bidirectional/

Answer 2

我想更好的方法是使用稍微改造你的实体设计。请参阅以下类图。您可以创建一个抽象的CriteriaEntity，它将criteriaId作为主键。请仔细选择子类的继承策略。如果条件实体相对简单，则考虑使用SINGLE_TABLE或移至TABLE_PER_CLASS。

@Inheritance(strategy = InheritanceType.SINGLE_TABLE)

您需要重新编写FieldCriteriaEntity以仅使用一个映射。请参阅以下

@Table(name = "FIELD_CRITERIA")
public class FieldCriteriaEntity implements Identifiable{

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "CRITERIA_KEY", unique = true, nullable = false)
    private Long id;

    @OneToOne(fetch = FetchType.EAGER, cascade =  CascadeType.ALL,optional=true)
    @JoinColumn(name="CRITERIA_ID")
    private CriteriaEntity criteria;
}

希望这有帮助！