TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing when I am doing merge

Question

Can anybody explain me why I am getting TransientObjectException when I doing merge. Issue is reproducing only when I create RuleTestEntitiy inside constructor of ActivityTestEntity as showed below. It doesn't appears if I do update or create.

Thanks in advance.

Here is a test:

@ContextConfiguration(locations = {
    "classpath:testApplicationContext_db.xml"})
public class TransientObjectExceptionTest extends  AbstractTestNGSpringContextTests{
@Autowired
SessionFactory sessionFactory;
@Test
public void testAddTestActivity(){
    Session session = sessionFactory.openSession();
    Transaction tx1 = session.beginTransaction();
    ActivityTestEntity newActivityEntity = new ActivityTestEntity();
    session.merge(newActivityEntity);
    tx1.commit();
    session.close();
    sessionFactory.close();
}

}

Exception: org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: com.xxx.RuleTestEntity

@Entity
@Table(name = "ACTIVITY_TEST")
public class ActivityTestEntity implements Serializable{
private static final long serialVersionUID = 4190826330152288861L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "ACTIVITY_ID", nullable = false)
private long id;
@OneToMany(mappedBy = "activity", cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval = true)
private Set<RuleTestEntity> rules = new HashSet<>();
public ActivityTestEntity() {
    RuleTestEntity rule = new RuleTestEntity();
    rule.setActivity(this);
    this.getRules().add(rule);
}
public long getId() {
    return id;
}
public void setId(long id) {
    this.id = id;
}
public Set<RuleTestEntity> getRules() {
    return rules;
}
public void setRules(Set<RuleTestEntity> rules) {
    this.rules = rules;
}

}

@Entity
@Table(name = "RULE_TEST")
public class RuleTestEntity implements Serializable {
private static final long serialVersionUID = -4208222848601642508L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "RULE_ID", nullable = false)
@XmlElement(name = Identifiable.ID_FIELD_NAME)
private long id;
@ManyToOne
@JoinColumn(name = "ACTIVITY_ID", nullable = true, updatable = false)
@XmlTransient
private ActivityTestEntity activity;
public ActivityTestEntity getActivity() {
    return activity;
}
public void setActivity(ActivityTestEntity activity) {
    this.activity = activity;
}
public long getId() {
    return id;
}
public void setId(long id) {
    this.id = id;
}
@Override
public boolean equals(Object o) {
    if (this == o) {
        return true;
    }
    if (o == null || getClass() != o.getClass()) {
        return false;
    }
    RuleTestEntity that = (RuleTestEntity) o;
    if (id != that.id) {
        return false;
    }
    return activity != null ? activity.equals(that.activity) : that.activity == null;
}
@Override
public int hashCode() {
    int result = (int) (id ^ (id >>> 32));
    result = 31 * result + (activity != null ? activity.hashCode() : 0);
    return result;
}

}

Answer 1

this exception is generated when you try to save an Entity referenced to an unsaved entity. you can either save the referenced entity first then save the entity or you can add cascade=CascadeType.All to the relations between the two of them.

Remove the code inside your constructor and then try this code:

    Session session = sessionFactory.openSession();
    Transaction tx1 = session.beginTransaction();
    RuleTestEntity rule = new RuleTestEntity();
    session.save(rule);
    session.refresh(rule);
    ActivityTestEntity newActivityEntity = new ActivityTestEntity();
    Set<RuleTestEntity> rules = new HashSet<>();
    rules.add(rule);
    session.merge(newActivityEntity);
    tx1.commit();
    session.close();
    sessionFactory.close();