How to map entity property to entities of inheritance SINGLE_TABLE in hibernate?

Question

I have entity hierarchy with inheriatnce type SINGLE_TABLE :

@Entity  
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)  
@DiscriminatorValue("junioruser")  
@DiscriminatorColumn(name = "dtype", discriminatorType = DiscriminatorType.STRING)  
.........  
public class JuniorUser  { 

The problem is how to map this JuniorUser entity and all its subclasses as property in Answer entity as :

@Entity  
public class Answer  {  
private JuniorUser user;  
.......................... 

If it is not possible then how can I map to 'user' property in Answer entity correct subclass of JuniorUser or JuniorUser itself using hibernate 4?

UPDATE: I do this to retrieve Answer and associated user:

Answer answer = sessionFactory.getCurrentSession().get(entityClass, id);

Asking for canonical name of related user

answer.getUser().getClass().getCanonicalName();

gives com.javahelp.domain.impl.JuniorUser_$$_javassist_3
Next asking for value of property dtype it gives 'junioruser'. The final thing is that all other properties of this user are null including user_id property.
I myself see that for retrieved answer I have related user which has dtype as 'expertuser'

Thank you!

Answer 1

The main problem here is misunderstanding fetch types.

FetchType.EAGER means load related entity properties from database when parent is loaded in one select. Create new instance of related entity and assign all values fetched from database to its properties. Related entity itself is also assigned to property of parent entity.

FetchType.LAZY means when parent is loaded from database create proxy of such related entity and assign proxy to parent entity property. To get any value of lazy loaded related entity it is needed to call methods of its proxy.