JPA and Generics

Question

Hi,
please consider the following code snippet:
@Entity
@Table(name = "MS")
@DiscriminatorColumn (name="TYPE",discriminatorType=DiscriminatorType.INTEGER)
public abstract class MS<T extends M> implements java.io.Serializable {
    @JoinColumn(name = "M_ID", referencedColumnName = "ID")
    @ManyToOne(fetch=FetchType.LAZY)
    private T m;
@Entity
@DiscriminatorValue("0")
public class BS extends MS<B> implements java.io.Serializable {
@Entity
@Table (name="M")
@DiscriminatorColumn (name="TYPE",discriminatorType=DiscriminatorType.INTEGER)
public abstract class M<T extends MS> implements java.io.Serializable {
    @OneToMany(mappedBy="m")
    private Set<T> ms = new HashSet<T>();
@Entity
@DiscriminatorValue("0")
public class B extends M<BS> implements java.io.Serializable {
}This compiles and deploys fine. However, at runtime JPA is not able
to figure out what m in the mappedBy attribute refers to.
It complains that it has a set of type BS which does not have the field m defined. This is true for BS
but its super class MS has this field defined.
So I wondering if this is a limitation of JPA or may be I configured something
wrong!? Is a scenario like above possible with the current JPA?
Thanks for any help.
regards.

Answer 1

No idea!? Let me give an example using Hibernate (you could replace it with JPA though):
B b = session.get(B.class, Long.valueOf(1));
Hibernate.initialize(b);In the initialize() process you get an exception, complaining that the Set cannot be resolved because the property m does not exist in class B (which is the type at runtime).
So I am wondering if it is currently possible to use generics in this way with JPA/Hibernate Entity Manager?