LazyInitializationException and transaction

[Gabriel Vargas]

Hi.

I get an LazyInitializationException when i try to use an entity bean (ejb3) in a backing bean (presentation layer) (jsf), because the entity bean is out of transaction defined in my business layer. How can i use my entity bean in my presentation layer?

[Sunil Dixit]

Hi,
Do you entity bean have any relationship with other bean ?
If yes and you are trying to fetch data using your parent entity,than you shd use aggressive fetching stg.
If you business say that you can't have aggressive fetching stg. than you need to populate the required data in you parent bean.
e.g.
Student -> Course
(1) (N)
So in student bean either you mark fetching stg as aggressive OR write necessary code in StudentBean to fetch the required data.
The exception which your talking abt is occured when you try to access something whose proxy is not initialise.
Hope that this will help you.

Cheers,
Sunil Dixit

[Gabriel Vargas]

Hi Sunil,

I try to put both aggresive and lazy strategies but its fails .I try to explain better. I have sessions beans than acts as facades to all my business services, these beans manages transactionality. These beans are called from jsf backing beans. The problem occur when i try to get an entity bean and use in a backing bean then i get this exception. I try to put transactionality in backing beans and it works, but it seems not good to me because i am mixing business layer and presentation layer, i want to keep transactionality in my business layer (session beans) and use results of entity beans in my backing beans. I'm usign JBoss and hibernate. Any idea how do this?

[Sunil Dixit]

Hi,
Thanks for giving this information,could you please post the piece of code which is used to get the data from the database.The reason why I am asking I need to have a look how you are fethcing the data from database using Hibernate.
Let me tell you how Hibernate works, when you try to load and object using Hibernate than your POJO class is being enhanced by Hibernate framework to PROXY which know how to get/set the details from database.This PROXY will work fine till the time you have vaild Tx/Session.
The time you close you Tx/Session than this PROXY is not valid,If you want to use your POJO object outside of Tx context and try to get some information which was not loaded during PROXY had valid Tx/context than you will get same exception.
So I want to have a look how you are usning Hibernate to get the information.
After seeing that I can tell you something.

Cheers,
Sunil Dixit

[Gabriel Vargas]

Hi Sunil.

First i show an entity, this is managed by JBoss and Hibernate with EJB3 spec.

/**
 * class represents a car
 */
@Entity
@Table(name = "carro")
public class Carro implements Serializable {

private static Logger logger = Logger.getLogger(Carro.class.getName());
 
/**
 * car's id
 */
private Long id;
 
/**
 * car's model
 */
private String modelo;

/**
 * car's revisions
 */
private List<Revision> revisiones;

/**
 * constructor without parameters
 */
public Carro() {
revisiones = new ArrayList<Revision>();
}

...
/**
     * copy entity into business object
     * 
     * @param carroBO
     */
public void copy(ICarroBO carroBO) {
placa = carroBO.getPlaca();
modelo = carroBO.getModelo();
}
 
/**
 * Returns the id.
     * @return Returns the id.
     */
    @Id
    @GeneratedValue
public Long getId() {
return id;
}
 
    /**
     * Assigns the id
     * @param id The id to set.
     */
public void setId(Long id) {
this.id = id;
}
 
/**
     * @return Returns the modelo.
     */
    @Column(nullable = false, length = 80)
public String getModelo() {
return modelo;
}
 
    /**
     * @param modelo The modelo to set.
     */
public void setModelo(String modelo) {
this.modelo = modelo;
}
 
/**
     * @return Returns the placa.
     */
    @Column(nullable = false, length = 80, unique = true)
public String getPlaca() {
return placa;
}
 
    /**
     * @param placa The placa to set.
     */
public void setPlaca(String placa) {
this.placa = placa;
}

/**
     * @return Returns the revisiones.
     */
@OneToMany(mappedBy="carro", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@JoinColumn(name="carro_id")
public List<Revision> getRevisiones() {
return revisiones;
}
 
/**
     * @param revisiones The revisiones to set.
     */
public void setRevisiones(List<Revision> revisiones) {
this.revisiones = revisiones;
}

public void addRevision(Revision revision) {
this.revisiones.add(revision);
revision.setCarro(this);
}

/**
 * convierte el entity a un objeto BO
 * @return ICarroBO
 */
public ICarroBO toCarroBO() {
ICarroBO carroBO = new CarroBO();
carroBO.setId(getId());
carroBO.setPlaca(getPlaca());
carroBO.setModelo(getModelo());
return carroBO;
}
}

/

As you can see is necesary construct a business object to manage object out of transaction defined in my facade session bean. My facade session bean looks like.

//@SecurityDomain("taller")
@Stateless
public class FachadaTallerImpl implements FachadaTallerLocal, FachadaTallerRemote {

//@Resource 
//private javax.ejb.SessionContext ctx;

@EJB(beanName="CarroDAOImpl")
private CarroDAO carroDAO;

@EJB(beanName="RevisionDAOImpl")
private RevisionDAO revisionDAO;

/**
 * persist the car BO
 * @param ICarroBO
 * @return ICarroBO
 */
@TransactionAttribute(value = TransactionAttributeType.REQUIRED)
public ICarroBO createCarro(ICarroBO carroBO) throws TallerException {
String placa = carroBO.getPlaca();       
Carro carro = carroDAO.findCarroPorPlaca(placa);

if(carro == null){
carro = new Carro(carroBO);
        carroDAO.create(carro);
return carro.toCarroBO();
} else {
//ctx.setRollbackOnly();
//String mensaje = Messages.getInstance().getMsg(
"premio.FachadaPremioSessionBean.catalogoExistente", new String[] {placa});
String mensaje = "taller.ejb.FachadaTallerImpl.createCarro: car " + carroBO.getPlaca() 
+ " exists";
throw new TallerException(mensaje);
}
}
 
...

And my jsf backing bean looks like:

public class CarroBean implements Serializable {

private static Logger logger = Logger.getLogger(CarroBean.class.getName());

/**
 * constructor sin parametros
 *
 */
public CarroBean() {
logger.info("Creando bean de sesi�n");
}

/**
 * create or update a car
 * @return return next view
 */
public String ingresar() {
FacesContext context = FacesContext.getCurrentInstance();
ICarroBO carroBO = (ICarroBO)context
.getExternalContext()
.getSessionMap()
.get("carroBO");
try {
FachadaTaller fachadaTaller = FachadaTallerLocator.getLocal();
logger.info("carroBO.id:" + carroBO.getId());
if ( carroBO.getId() == null ) {
fachadaTaller.createCarro(carroBO);
} else {
fachadaTaller.saveCarro(carroBO);
}
return "success";
} catch (TallerException te) {
logger.error("error 1:"+te.toString());
context.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_ERROR
, te.toString(), ""));
} catch (Exception e) {
logger.error("error 2:"+e.toString());
String msg = "taller.facesbean.CarroBean: excepcion " + e.getMessage();
            context.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_ERROR, msg, ""));
}
return null;
}
}

My entity bean called Car is used bellow my session bean because transaction is defined in this level, if i try to use that in my backing bean i get that exception, the only solution than i can find is put transaction in my backing bean but it seems not good to me or use the busines object as show in example , i think there is another way to do this better.
[ July 10, 2007: Message edited by: Juan Gabriel Vargas Bola�os ]

[Gabriel Vargas]

Hi, somebody can help me