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https://issues.apache.org/jira/browse/AVRO-1340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16420956#comment-16420956
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Doug Cutting commented on AVRO-1340:
------------------------------------
The following changes to idl.jj work for me:
+++ b/lang/java/compiler/src/main/javacc/org/apache/avro/compiler/idl/idl.jj
@@ -1099,13 +1099,16 @@ Schema EnumDeclaration():
{
String name;
List<String> symbols;
+ String defaultSymbol = null;
}
{
"enum"
name = Identifier()
symbols = EnumBody()
+ [ <EQUALS> defaultSymbol=Identifier() ]
{
- Schema s = Schema.createEnum(name, getDoc(), this.namespace, symbols);
+ Schema s = Schema.createEnum(name, getDoc(), this.namespace, symbols,
+ defaultSymbol);
names.put(s.getFullName(), s);
return s;
}
Does that not work for you?
> use default to allow old readers to specify default enum value when
> encountering new enum symbols
> -------------------------------------------------------------------------------------------------
>
> Key: AVRO-1340
> URL: https://issues.apache.org/jira/browse/AVRO-1340
> Project: Avro
> Issue Type: Improvement
> Components: spec
> Environment: N/A
> Reporter: Jim Donofrio
> Priority: Minor
>
> The schema resolution page says:
> > if both are enums:
> > if the writer's symbol is not present in the reader's enum, then an
> error is signalled.
> This makes it difficult to use enum's because you can never add a enum value
> and keep old reader's compatible. Why not use the default option to refer to
> one of enum values so that when a old reader encounters a enum ordinal it
> does not recognize, it can default to the optional schema provided one. If
> the old schema does not provide a default then the older reader can continue
> to fail as it does today.
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