Queries on an interface

Question

I was hoping I could query on an interface that has multiple classes
implementing it.
I have an interface named net.sundog.listserv.Subscriber
and two concrete JDO enhanced classes: net.sundog.customer.Employee and
net.sundog.customer.Customer.
When I run the query:
Query query = pm.newQuery(Subscriber.class);
SortedSet set;
try {
set = new TreeSet((Collection) query.execute());
} finally {
query.closeAll();
I get the following error:
Multiple concrete implementations of the abstract class
"net.sundog.listserv.Subscriber" are registered: "[class
net.sundog.customer.Employee, class net.sundog.customer.Customer]". Only a
single concrete inheritance hierarchy can be used for an abstract class or
interface.
I understand that to mean I can only have one JDO enhanced class that
implements the "Subscriber" inteface. I tried adding a class-column to both
the Customer and the Employee JDO metadata, but that didn't help any.
Is this actually a limitation of Kodo, or is there something I can do to get
around it, and if it is a limitation is there any plans on removing it
(hopefully in 2.5)?
Nathan

Answer 1

Great, thanks. When you query on an interface, can you use JDOQL to limit
what objects you get back, since the interfaces don't have attributes
defined?
"Abe White" <[email protected]> wrote in message
news:[email protected]..
Yes, 2.5 includes the ability to query on interfaces. It transparently
performs the query on all implementors of the interface and merges the
results. You can pick up a beta right now:
http://solarmetric.com/Software/beta/2.5.0