Hello there,
Not sure if posting in the correct section as my problem is mostly related to hibernate-jpamodelgen.
Anyway, here is the problem.
I got an Eclipse project using JPA configured to generate static metamodel with the hibernate-jpamodelgen library.
It appears that one of the generated classes contains an error, related to generic types. It makes my project unable to compile.
But what is strange, is when I generate the metamodel with maven, the error is gone, as the generic types are correctly processed.
Here is the setup
An JOINED inheritance of a generic AbstractItem<F, V> defined by an IItem<F,V> interface:
Code:
public interface IItem<F, V> {
F getField();
void setField(F field);
V getValue();
void setValue(V value);
}
The AbstractItem<F,V> implementation:
Code:
@Entity
@Inheritance(strategy=InheritanceType.JOINED)
public abstract class AbstractItem<F, V> implements IItem<F, V>{
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;
@ManyToMany(mappedBy = "items", fetch = FetchType.LAZY, cascade = { CascadeType.MERGE, CascadeType.REFRESH, CascadeType.PERSIST })
private Set<Holder> entities = new HashSet<Holder>();
/* getters & setters */
}
An implementation of this Item:
Code:
@Entity
public class Item extends AbstractItem<String, Long> {
@Basic
private String field;
@Basic
private Long value;
/* getters & setters impl */
}
And finally, an object Holder that hold a Set of AbstractItem<?,?> which is an @Entity:
Code:
@Entity
public class Holder {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;
@ManyToMany(fetch = FetchType.LAZY, cascade = { CascadeType.MERGE, CascadeType.REFRESH, CascadeType.PERSIST })
private Set<AbstractItem<?, ?>> items = new HashSet<AbstractItem<?,?>>();
public Holder(){
super();
}
/* getters & setters */
}
The problem appear with the static metamodel of the Holder class generated by eclipse APT which looks like this:
Code:
@Generated(value = "org.hibernate.jpamodelgen.JPAMetaModelEntityProcessor")
@StaticMetamodel(Holder.class)
public abstract class Holder_ {
public static volatile SingularAttribute<Holder, Integer> id;
public static volatile SetAttribute<Holder, AbstractItem<F,V>> item;
}
You can see that the second attribute declares unknown types (<F,V>), which lead to a compile error.
But, when generating the metamodel with maven, it is correctly done, as it removes the unknown types :
Code:
@Generated(value = "org.hibernate.jpamodelgen.JPAMetaModelEntityProcessor")
@StaticMetamodel(Holder.class)
public abstract class Holder_ {
public static volatile SingularAttribute<Holder, Integer> id;
public static volatile SetAttribute<Holder, AbstractItem> item;
}
It is quite a problem as this could change the workflow of our development team if no workaround is found, and I would really like to keep this JPA mapping, as it allows a real object inheritance through JPA.
I even tried checking out the latest sources of the hibernate-jpamodelgen lib, adding a test case for this setup, but the result were correct.
What do you think could cause such a difference ?
I can only see a different execution environment of the library between Eclipse APT and maven, but I don't know what to do to correctly configure eclipse to do it.
Thank you for taking the time to read me.
Environment details:
- Updated Eclipse Juno 4.2
- hibernate-jpamodelgen-1.2.0.Final & hibernate-jpamodelgen-1.3.0-SNAPSHOT
- hibernate-core-4.1.2.Final
- hibernate-jpa-2.0-api-1.0.1.Final
- JDK 1.6.0_45
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