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Avro, mail # user - Problems with SortedKeyValueFile.Reader: Generic vs Specific Interface


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Jeremy Lewi 2012-12-16, 07:06
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Re: Problems with SortedKeyValueFile.Reader: Generic vs Specific Interface
Doug Cutting 2012-12-17, 18:31
A GenericDatumReader will never return a specific record.  Perhaps
this code should use ReflectDatumReader (which will return a java
class if the named class is loaded or else GenericRecord).  The
changes will be deeper, since this builds on AvroKeyValue which also
assumes generic, so I can't tell at a glance how difficult this would
be.

Doug

On Sat, Dec 15, 2012 at 11:06 PM, Jeremy Lewi <[EMAIL PROTECTED]> wrote:
> HI avro-users,
>
> I'm having issues with SortedKeyValueFile.Reader. Even though the return
> type of get is a specific record type, the actual instance returned has type
> GenericRecord. How do I convert this GenericRecord into an instance of my
> specific record?
>
> Looking at the source code SortedKeyValueFile is using the Generic interface
> to read the data. But the return type for get is V where I have set V to be
> a specific record. e.g
>
> SortedKeyValueFile.Reader<CharSequence, GraphNodeData> where GraphNodeData
> is one of my avro records.
>
> I don't understand how  this code compiles since the return type is
> V=GraphNodeData and a GenericRecord can't be cast to a GraphNodeData.
>
> Thoughts?
>
> Thanks
> J
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Jeremy Lewi 2012-12-22, 16:53