Force JPA load Identity ID after Insert

When you have an ID into your Entity Classe from Database and that is Identity, if you do an insert action the ID of this Entity isn't reloaded by default with the ID that was generated by Database, through JPA.

A sample of an ID of Identity kind:

@Id
@Basic(optional = false)
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name = "Id")
private Integer id;


To refresh the ID value with the ID that was generated by the Database on insert action, you need put more this below in your AbstractFacade.Create(EntityClass):

getEntityManager().flush();
getEntityManager().refresh(entity);


• getEntityManager().flush() - Will do the commit to Database execute the insert action.


• getEntityManager().refresh(entity) - Will refresh the entity object with a new ID that was inserted.

Full sample of the AbstractFacade.java:

package org.test.ejb;

import java.util.List;
import javax.persistence.EntityManager;

public abstract class AbstractFacade {
private Class entityClass;

public AbstractFacade(Class entityClass) {
this.entityClass = entityClass;
}

protected abstract EntityManager getEntityManager();

public void create(T entity) {
getEntityManager().persist(entity);
getEntityManager().flush();
getEntityManager().refresh(entity);
}

public void edit(T entity) {
getEntityManager().merge(entity);
}

public void remove(T entity) {
getEntityManager().remove(getEntityManager().merge(entity));
}

public T find(Object id) {
return getEntityManager().find(entityClass, id);
}

public List findAll() {
javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
cq.select(cq.from(entityClass));
return getEntityManager().createQuery(cq).getResultList();
}

public List findRange(int[] range) {
javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
cq.select(cq.from(entityClass));
javax.persistence.Query q = getEntityManager().createQuery(cq);
q.setMaxResults(range[1] - range[0]);
q.setFirstResult(range[0]);
return q.getResultList();
}

public int count() {
javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
javax.persistence.criteria.Root rt = cq.from(entityClass);
cq.select(getEntityManager().getCriteriaBuilder().count(rt));
javax.persistence.Query q = getEntityManager().createQuery(cq);
return ((Long) q.getSingleResult()).intValue();
}
}


If you publish your JPA Create action in a Web Services, you will need return to client side an Entity instance to client know what is the new ID. Cause the Entity instance of the Client side can't be refresh with changes inside Server.
Like:

@WebMethod(operationName = "create")
public BusinessEntity create(@WebParam(name = "businessEntity")
BusinessEntity businessEntity) {
ejbRef.create(businessEntity);
return businessEntity;
}