[AVRO-1118] Specifying null as default of a union only works if null is specified as first type in the union

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 1.6.3
• Assignee: Unassigned
• Reporter: Mike Percy
• Created: 20/Jun/12 02:47
• Updated: 03/Aug/18 12:09
• Resolved: 20/Jun/12 06:20

Description

There is some unexpected behavior I am coming across where if I specify a union as such:

"type": ["string", "null"],
"default": null

I get an Exception:

Exception in thread "main" org.apache.avro.AvroTypeException: Non-string default value for string: null
at org.apache.avro.io.parsing.ResolvingGrammarGenerator.encode(ResolvingGrammarGenerator.java:363)
at org.apache.avro.io.parsing.ResolvingGrammarGenerator.encode(ResolvingGrammarGenerator.java:350)
at org.apache.avro.io.parsing.ResolvingGrammarGenerator.getBinary(ResolvingGrammarGenerator.java:293)
at org.apache.avro.io.parsing.ResolvingGrammarGenerator.resolveRecords(ResolvingGrammarGenerator.java:271)
at org.apache.avro.io.parsing.ResolvingGrammarGenerator.generate(ResolvingGrammarGenerator.java:118)
at org.apache.avro.io.parsing.ResolvingGrammarGenerator.generate(ResolvingGrammarGenerator.java:50)
at org.apache.avro.io.ResolvingDecoder.resolve(ResolvingDecoder.java:82)
at org.apache.avro.io.ResolvingDecoder.<init>(ResolvingDecoder.java:46)
at org.apache.avro.io.DecoderFactory.resolvingDecoder(DecoderFactory.java:307)
at org.apache.avro.generic.GenericDatumReader.getResolver(GenericDatumReader.java:118)
at org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:133)
at org.apache.avro.file.DataFileStream.next(DataFileStream.java:233)
at org.apache.avro.file.DataFileStream.next(DataFileStream.java:220)
...

Whereas if I specify the schema as:

"type": ["null", "string"],
"default": null

It works as expected.