Spring Boot & Hibernate - identifier of an instance of x was altered to null

Question

We have a super class for all entities called Heartcore with @MappedSuperclass .

@Id
private String id;

@Column(nullable = false)
@NonNull
private String uuid;

@NonNull
@Column(nullable = false)
private String kanton;

// specific Setter
public void setKanton(String kanton) {
  if (kanton != null) {
    id = uuid + "_" + kanton;
  }
  this.kanton = kanton;
}

public void setUuid(String uuid) {
  if (kanton != null) {
    id = uuid + "_" + kanton;
  }
  this.uuid = uuid;
}

I have the following unidirectional one-to-one relation:

Child-Entity

class OtoUniChild extends Heartcore {

@Id
private String id;

@OneToOne
@MapsId
private OtoUniParent otoUniParent;

public void setOtoUniParent(OtoUniParent otoUniParent) {
    if (otoUniParent != null) {
        if (StringUtils.isNoneBlank(otoUniParent.getUuid(), otoUniParent.getKanton())) {
            this.otoUniParent = otoUniParent;
            setUuid(otoUniParent.getUuid());
            setKanton(otoUniParent.getKanton());
            return;
        }
        throw new InvalidObjectException("Es wurde ein invalides Objekt übergeben!");
    }
    this.otoUniParent = null;
}

When I persist a parent and a child and then try to get a child from the child repository with findById(149727fd-b0ce-4069-bcd9-d67fdbe69021_SG) I just got the error "org.springframework.orm.jpa.JpaSystemException: identifier of an instance of x.data.OtoUniChild was altered from 149727fd-b0ce-4069-bcd9-d67fdbe69021_SG to null;" . I don't know how this can happen!

*Spring Boot v.1.5.8.RELEASE

Answer 1

I believe this is due to doubly defined @Id in your OtoUniChild class:

• once in Heartcore superclass.
• once in the entity itself

While such re-definition is not allowed with @MappedSuperclass , you happen to re-define it with same name and type. However, you still can expect some methods to see the former, and some the latter fields.