JPA: Override Auto generated ID [duplicate]

Question

I have following definition in Employee class

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "employee_id")
private Integer employeeId;

Now I want to import existing employees with existing employee IDs. Even if I set the employee ID before saving, the assigned ID is ignored and auto incremented ID is stored. How do we override this?

I had similar problem for composite key which has been explained here

Answer 1

I wrote my own generator to solve the issue.

public class UseExistingIdOtherwiseGenerateUsingIdentity extends IdentityGenerator {

    @Override
    public Serializable generate(SharedSessionContractImplementor session, Object object) throws HibernateException {
        Serializable id = session.getEntityPersister(null, object).getClassMetadata().getIdentifier(object, session);
        return id != null ? id : super.generate(session, object);
    }
}

and use it like this: (replace the package name)

@Id
@GenericGenerator(name = "UseExistingIdOtherwiseGenerateUsingIdentity", strategy = "{package}.UseExistingIdOtherwiseGenerateUsingIdentity")
@GeneratedValue(generator = "UseExistingIdOtherwiseGenerateUsingIdentity")
@Column(unique = true, nullable = false)
protected Integer id;

Answer 2

You cannot override it. First of all JPA do not provide way to do it. Second problem is that GenerationType.AUTO can produce such a column type that will not accept user assigned value via SQL statement.

Perform import of data manually and do not try to use application itself as an import tool.