Hibernate - 同步映射同一列的两个属性

Question

Is it possible to keep sync two properties on the same entity mapped to the same column (with basic JPA, or with hibernate)?

I have two properties:

@JoinColumn(referencedColumnName = "id", insertable = false, name = "parent", updatable = false)
@ManyToOne(fetch = FetchType.LAZY)
private Person parent;
@Column(name = "parent")
private Integer parentId;

Basically, I would like the following:

System.out.println(element.getParentId());
System.out.println(element.getParent().getId());
element.setParentId(2);
System.out.println(element.getParentId());
System.out.println(element.getParent().getId());

This to print "3,3,2,2" instead of "3,3,2,3".

Is it possible (without writing a custom lazy-loading on the getParent() getter?)

Thx in advance

Answer 1

IIRC, Hibernate will not do that for you. You're the one responsible if you have something like that (I remembered doing something similiar).

The first solution will be to save the entity first, then refresh using the entity manager.

element.setParentId(2);
entityManager.merge(element);
entityManager.refresh(element);

Refresh will make it fetch the object from the database again, and it will have the correct value.

The second option which I did, was to change the setter of the entity to maintain the state. Something like:

public void setParent(Parent parent) {
    this.parent = parent;
    parentId = parent.id;
}

Answer 2

Try this

@JoinColumn(referencedColumnName = "id", insertable = false, name = "parent")
@ManyToOne(fetch = FetchType.LAZY)
private Person parent;


@Column(name = "parent")
private Integer parentId;

If that don't work:

Try this if parentId is the primary key of the Parent entity:

@JoinColumn(referencedColumnName = "id", insertable = false, name = "parent")
@ManyToOne(fetch = FetchType.LAZY)
private Person parent;

@Id
@GeneratedValue(strategy = GenerateType.AUTO)
@Column(name = "parent")
private Integer parentId;

Try this:

@JoinColumn(referencedColumnName = "id", name = "parent")
@ManyToOne(fetch = FetchType.LAZY)
private Person parent;


@Column(name = "parent")
private Integer parentId;

If that don't work:

Try this:

@JoinColumn(name = "parent")
@ManyToOne(fetch = FetchType.LAZY)
private Person parent;


@Column(name = "parent")
private Integer parentId;

Answer 3

You can have two properties for the same column like this :

@JoinColumn(name = "CGRADO_CODIGO", referencedColumnName = "CGRADO_CODIGO")
    @ManyToOne
    @NotFound(action=NotFoundAction.IGNORE)
    private SipreGrado                  sipreGrado;

    @Column(name = "CGRADO_CODIGO",insertable=false,updatable=false)
    private String                      sipreGradoCodigo;

Your output in the inspect code will be like this :

sipreGradoCodigo   "001"
sipreGrado         null

or

sipreGradoCodigo   "001"
sipreGrado         Entity SipreGrado ["001","other property","etc"]

Remember if you have sometimes the entity NULL you can skip it with that annotation

@NotFound(action=NotFoundAction.IGNORE)

Also,Remember to set

insertable=false,updatable=false 

for the one that you dont want to include in the insert/update queries.