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https://issues.apache.org/jira/browse/AVRO-1898?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thiruvalluvan M. G. closed AVRO-1898.
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Closing issues that got resolved in earlier releases.
> C++ library cannot parse unions with default values
> ---------------------------------------------------
>
> Key: AVRO-1898
> URL: https://issues.apache.org/jira/browse/AVRO-1898
> Project: Apache Avro
> Issue Type: Bug
> Components: c++
> Affects Versions: 1.8.1
> Reporter: Hua Zhang
> Assignee: Hua Zhang
> Priority: Major
>
> I have a Avro file generated by the Java library, and when I tried to read it
> using the C++ library, I got:
> Unexpected type for default value: Expected 6, but found 1
> Which basically says the default value should be of type Object, but got type
> Boolean. After some investigation, I found the exception is thrown when
> parsing the default value of a union. Looks like the C++ library requires the
> default value of a union to be an object. This is different from what the
> Avro specification says, that the default value of a union should be of the
> first type in the union.
> This field is causing the problem:
> {
> "name" : "fake_name",
> "type" : [ "boolean", "null" ],
> "default" : false
> }
> From the code the C++ library is expecting:
> {
> "name" : "is_track_mau30",
> "type" : [ "boolean", "null" ],
> "default" : {"boolean": false}
> }
> The related code is in impl/Compiler.cc, line 284. If I change it to the
> following, the Avro file can be parsed:
> {code}
> GenericUnion result(n);
> result.selectBranch(0);
> result.datum() = makeGenericDatum(n->leafAt(0), e, st);
> return GenericDatum(n, result);
> {code}
> Why is the C++ library behaves different than the specification? Can/should
> it be changed to follow the specification? It will be a breaking change
> though.
> Thanks and I'll be happy to contribute this change if it's deemed appropriate.
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