object references an unsaved transient instance - save the transient instance before flushing: com.example.model.Salutation

Question

I have two model class, User and Salutation as below. Foreign key (salutation_id) in User table is optional. To save User object when I flush on session object right after merge, I am getting below error.

Data in table Salutation have been inserted independent of User table. When I am trying to save User object having salutation_id as null, it throws this error.

Any help would be appreciable.

@Entity
@Table(name = "user")
public class User implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(unique = true, nullable = false)
    private String userName;

    @ManyToOne
    @JoinColumn(name = "salutation_id")
    private Salutation salutationRef;

    //Getter and Setter
}

@Entity
@Table(name = "salutation")
public class Salutation implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @ElementCollection
    @LazyCollection(LazyCollectionOption.FALSE)
    @OneToMany(mappedBy = "salutationRef")
    private List<Salutation> salutations;

    //Getter and Setter

}



public Object create(Object object) {
    Session session = sessionFactory.getCurrentSession();
    Transaction txn = session.beginTransaction();

    try {
        object = (Object) session.merge(object);
        session.flush();    //Getting error at this line object references an unsaved transient instance - save the transient instance before flushing: com.example.model.Salutation
        txn.commit();
    } catch (Exception e) {
        txn.rollback();
        e.printStackTrace();
    }

    return object;
}

Thanks for your help.

Eugene Eugene · Accepted Answer · 2016-11-28T23:56:16

I am not an expert with Hibernate, but according to Documentation for merge() here

The given instance does not become associated with the session.

I would suggest to fetch Entity in current Session, change fields' values and then flush it.

Or, In case of new Entity -- save() it.

Also. As far as I know, calling Transaction.commit() performs session flushing, so no need to do it manually after

object references an unsaved transient instance - save the transient instance before flushing: com.example.model.Salutation

2 Answers