JPA/Hibernate: How to persist duplicate values in same session for field having @Id annotation?

Question

Customer said no Primary Key Required in Child Table. So Child table has two column "ID" and "Value" where ID can be duplicated.

When i remove @Id then hibernate says "No identifier specified for entity"

When i keep @Id in code then hibernate says "javax.persistence.EntityExistsException: a different object with the same identifier value was already associated with the session" ; while persisting

So crux is that i need to keep @Id but how to persist two same ID in one session with @Id annotation.

Following is code:

Main Entity:

public class CustomerAgreement implements Serializable {

    @OneToMany(mappedBy = "customerAgreement", orphanRemoval = true, fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST})
    private List<CustomerAgreementComputerAttachments> autoAttachComputersFromOrganizations;

Composed Entity:

public class CustomerAgreementComputerAttachments implements Serializable{

    private static final long serialVersionUID = 1L;
    @Id
    @ManyToOne
    @JoinColumn(name = "ID")
    private CustomerAgreement customerAgreement;

Main Program:

  public static List<CustomerAgreement> create() {
        List<CustomerAgreement> li = new ArrayList<CustomerAgreement>();
        CustomerAgreement cAgreement = new CustomerAgreement();
        cAgreement.setId(2222l);
        cAgreement.setName("Tillu");;
        cAgreement.setCustomerId("140");


        List<CustomerAgreementComputerAttachments> catl = new ArrayList<>();
        CustomerAgreementComputerAttachments catt = new CustomerAgreementComputerAttachments();
        catt.setAttachmentValue("TEST");
        catt.setCustomerAgreement(cAgreement);
        CustomerAgreementComputerAttachments tatt = new CustomerAgreementComputerAttachments();
        tatt.setAttachmentValue("TESTy");
        tatt.setCustomerAgreement(cAgreement);
        catl.add(catt);
        catl.add(tatt);
        cAgreement.setAutoAttachComputersFromOrganizations(catl);



        li.add(cAgreement);
        return li;
    }
    public static void main(String[] args) {

        EntityManagerFactory emf = Persistence.createEntityManagerFactory("IntegratorMasterdataPU");
        em = emf.createEntityManager();
        em.getTransaction().begin();
        for(CustomerAgreement ca: create()) {

            em.persist(ca);

        }
        em.getTransaction().commit();

    }

Then you probably want `CustomerAgreement` to be an `Embeddable` and use `ElementCollection`. Additionally, drop `Serializable`; it's useless and adds noise. — chrylis -cautiouslyoptimistic-, Dec 11 '19 at 04:53
Used ElementCollection(targetClass = CustomerAgreementComputerAttachments.class) .... on OneToMany.... and on this class used Embeddable..... Is it fine way to do — fatherazrael, Dec 11 '19 at 05:01
@chrylis-onstrike-: It then says Composite-id class must implement Serializable: com.evry.integrator.snow.dao.model.CustomerAgreementComputerAttachments... — fatherazrael, Dec 11 '19 at 05:11

Alan Hay · Accepted Answer · 2019-12-12T08:29:05.333

An Entity must be identifiable by a unique key. This doesn't need to correspond to any database primary key but there must a unique column or columns that can be used to identity an entity.

If this is not possible, then you need to make CustomerAgreementComputerAttachment an @Embeddable.

An @Embeddable unlike an entity has no independent identity (no @ID). See further here:

What is difference between @Entity and @embeddable

@Entity
public class CustomerAgreement  {

    @ElementCollection
    @JoinTable(name="...", joinColumn = "id")
    private List<CustomerAgreementComputerAttachment> attachments;
}

and

@Embeddable
public class CustomerAgreementComputerAttachments {

    //No back reference to CustomerAgreement   
    //Other fields as required.
}

Note in particular that the embeddable has no `@Id`. – chrylis -cautiouslyoptimistic- Dec 11 '19 at 21:04 — chrylis -cautiouslyoptimistic-, Dec 11 '19 at 21:04

JPA/Hibernate: How to persist duplicate values in same session for field having @Id annotation?

1 Answers1