With JDO, is it possible to query for all objects that implement a particular interface?

Question

I tried using the following query:

Query q = getPersistenceManager().newQuery(
getPersistenceManager().getExtent(ICommentItem.class, false)
);

but got:

org.datanucleus.exceptions.NoPersistenceInformationException: The class
"com.sampleapp.data.dataobjects.ICommentItem" is required to be persistable yet no Meta -Data/Annotations can be found for this class. Please check that the Meta-Data/annotations is defined in a valid file location.

I saw in the Datanucleus forum somebody suggested (a few years ago) using :

<interface name=IComment/> 

I tried that but it didn't create any table when I ran schema-update. Is tag still relavent? I coudnt see anything in docs on it.

I also tried :

<class name=IComment/>

But that gave this error when running schema-create:

SEVERE: Error thrown enhancing with ASMClassEnhancer java.lang.NullPointerException at org.datanucleus.enhancer.asm.method.DefaultConstructor.execute(DefaultConstructor.java:63) at org.datanucleus.enhancer.asm.JdoClassAdapter.visitEnd(JdoClassAdapter.java:317) at org.objectweb.asm.ClassReader.accept(Unknown Source) at org.objectweb.asm.ClassReader.accept(Unknown Source) at org.datanucleus.enhancer.asm.ASMClassEnhancer.enhance(ASMClassEnhancer.java:388) at org.datanucleus.enhancer.DataNucleusEnhancer.enhanceClass(DataNucleusEnhancer.java:1035) at org.datanucleus.enhancer.DataNucleusEnhancer.enhance(DataNucleusEnhancer.java:609) at org.datanucleus.enhancer.DataNucleusEnhancer.main(DataNucleusEnhancer.java:1316) Oct 23, 2010 6:46:33 PM org.datanucleus.enhancer.DataNucleusEnhancer addMessage INFO: ERROR (PersistenceCapable) : com.sampleapp.data.dataobjects.ICommentItem Oct 23, 2010 6:46:33 PM org.datanucleus.enhancer.asm.ASMClassEnhancer enhance INFO: Class "com.sampleapp.data.dataobjects.Article" is already enhanced. Oct 23, 2010 6:46:33 PM org.datanucleus.enhancer.DataNucleusEnhancer addMessage SEVERE: DataNucleus Enhancer completed with an error. Please review the enhancer log for full details. Some classes may have been enhanced but some caused errors Failure during enhancement of classes - see the log for details org.datanucleus.exceptions.NucleusException: Failure during enhancement of classes - see the log for details at org.datanucleus.enhancer.DataNucleusEnhancer.enhance(DataNucleusEnhancer.java:620) at org.datanucleus.enhancer.DataNucleusEnhancer.main(DataNucleusEnhancer.java:1316)

Answer 1

Turns out this is not supported at this time but is planned to be added in version 2.2.0M3