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https://issues.apache.org/jira/browse/CRUNCH-548?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14638731#comment-14638731
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Gabriel Reid commented on CRUNCH-548:
-------------------------------------
Patch makes sense looks good to me, although the valueClass constructor
parameter to AvroDeepCopier can also be removed now.
I looked around a bit and tried to think of any other spots where a similar
change would be useful, but I can't think of any. I think that Avro reflection
is currently the only place where we've got a potential for a user-specified
implementation of a value class.
> getDetachedValue calls to AvroReflectDeepCopier throw InstantiationException
> on non-concrete types
> --------------------------------------------------------------------------------------------------
>
> Key: CRUNCH-548
> URL: https://issues.apache.org/jira/browse/CRUNCH-548
> Project: Crunch
> Issue Type: Bug
> Reporter: Adric Eckstein
> Attachments: CRUNCH-548.patch
>
>
> 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.
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