>
> - Datanucleus now supports polymorphic relationships.
> http://code.google.com/p/datanucleus-appengine/issues/detail?id=153
>
Can anyone explain to me how to use this? I've got a simple example that
doesn't work (see below). Sofa extends Furniture, but when I try to persist
a collection of furniture in a House, I get the following:
"java.lang.UnsupportedOperationException: Received a child of type
modeltest.server.Sofa for a field of type modeltest.server.Furniture.
Unfortunately polymorphism in relationships is not yet supported."
I'm using the 1.5.1 SDK.
// imports
@PersistenceCapable
public class House {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
@Extension(vendorName = "datanucleus", key = "gae.encoded-pk", value =
"true")
String id;
@Persistent ArrayList<Furniture> furniture;
House() {
furniture = new ArrayList<Furniture>();
furniture.add(new Sofa());
}
}
// imports...
@PersistenceCapable
@Inheritance(strategy = InheritanceStrategy.SUBCLASS_TABLE)
public abstract class Furniture {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
@Extension(vendorName = "datanucleus", key = "gae.encoded-pk", value =
"true")
String id;
}
// imports
@PersistenceCapable
public class Sofa extends Furniture {
}
Best,
~Owen
> --
> Johan Euphrosine (proppy)
> Developer Programs Engineer
> Google Developer Relations
>
>
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