[CRUNCH-548] getDetachedValue calls to AvroReflectDeepCopier throw InstantiationException on non-concrete types

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.13.0
• Assignee: Josh Wills
• Reporter: Adric Eckstein
• Created: 21/Jul/15 15:32
• Updated: 06/Aug/15 04:39
• Resolved: 23/Jul/15 17:04

Description

A common use case with avro reflection is to operate on an abstract class or interface which is serialized using a schema based on a concrete subclass (or union of subclasses).

@org.apache.avro.reflect.Union(

{ Foo1.class }

)
public interface Foo {
public String getFoo();
}
public class Foo1 implements Foo {
private final Double value = 1.0;
@Override
public String getFoo()

{ return value.toString(); }

}

When trying to operate on this type within crunch, calls to getDetachedValue() will throw an InstantiationException:

AvroType<Foo> ptype = Avros.reflects(Foo.class, ReflectData.get().getSchema(Foo.class));
ptype.initialize(new Configuration());
Foo copy1 = ptype.getDetachedValue(new Foo1());

Exception in thread "main" org.apache.crunch.CrunchRuntimeException: java.lang.InstantiationException: org.mitre.caasd.tt.DeepCopyTest$Foo
at org.apache.crunch.types.avro.AvroDeepCopier$AvroReflectDeepCopier.createNewInstance(AvroDeepCopier.java:158)

One solution would be to augment the createNewInstance() method in AvroReflectDeepCopier to create a new instance based on the source object class, rather than the type class. This would generally be desirable for any union cases where the source is a subclass of the type class.