While using Hibernate annotations to implement a @OneToOne relationship where the entities are joined by primary key (@PrimaryKeyJoinColumn) I kept encountering a relatively infamous Exception:
IdentifierGenerationException: attempted to assign id from null one-to-one property
I discovered that my issue could easily be resolved by adding "optional=false" to the dependent side of the relation. Here's a brief summary of the relevant related code.
@Entity
public class Profile implements Serializable {
@OneToOne(mappedBy="profile", optional=false, fetch=FetchType.LAZY)
public Hospital getHospital() {
return hospital;
}
@Id @GeneratedValue(generator="foreign")
@GenericGenerator(name="foreign", strategy = "foreign", parameters={
@Parameter(name="property", value="hospital")
})
public Long getId() {
return this.id;
}
}
@Entity
public class Hospital implements Serializable {
@OneToOne(cascade = CascadeType.ALL,fetch=FetchType.LAZY)
@PrimaryKeyJoinColumn
public Profile getProfile() {
return profile;
}
@Id @GeneratedValue(strategy=GenerationType.AUTO)
public Long getId() {
return id;
}
}
Eric Simmerman
