I'm currently trying to "translate" the following Java class to an equivalent Scala class. It's part of a JavaEE6-application and i need it to use the JPA2 MetaModel.
import javax.persistence.metamodel.SingularAttribute;
import javax.persistence.metamodel.StaticMetamodel;
@StaticMetamodel(Person.class)
public class Person_ {
public
static volatile SingularAttribute<Person, String> name;
}
A dissassembling of the compiled class file reveals the following information for the compiled file:
> javap Person_.class :
public class model.Person_ extends java.lang.Object{
public
static volatile javax.persistence.metamodel.SingularAttribute name;
public model.Person_();
}
So now i need an equivalent Scala file that has the same structure, as JPA depends on it, cause it resolves the attributes by
reflection to make them accessible at runtime. So the main problem i think is that the attribute is
static, but the Annotation has to be on an (Java)Object (i guess)
My first naive attempt to create a Scala equivalent is the following:
@StaticMetamodel(classOf[Person])
class Person_
object Person_ {
@volatile var name:SingularAttribute[Person, String] = _;
}
But the resulting classfile is far away from the Java one, so it doesn't work. When trying to access the attributes at runtime, e.g. "Person_.firstname", it resolves to null, i think JPA can't do the right
reflection magic on the compiled classfile (the Java variant resolves to an instance of org.hibernate.ejb.metamodel.SingularAttributeImpl at runtime).
> javap Person_.class :
public class model.Person_ extends java.lang.Object implements scala.ScalaObject{
public
static final void name_$eq(javax.persistence.metamodel.SingularAttribute);
public
static final javax.persistence.metamodel.SingularAttribute name();
public model.Person_();
}
> javap Person_$.class :
public final class model.Person__$ extends java.lang.Object implements scala.ScalaObject
public
static final model.Person__$ MODULE$;
public
static {};
public javax.persistence.metamodel.SingularAttribute name();
public void name_$eq(javax.persistence.metamodel.SingularAttribute);
}
So now what i'd like to know is if it's possible at all to create a Scala equivalent of the Java class? It seems to me that it's absolutely not, but maybe there is a workaround or something (except just using Java, but i want my app to be in Scala where possible)
Any ideas, anyone? Thanks in advance!
