[jira] [Commented] (AVRO-1817) Allow enums to be "promoted" to strings

["Sean Busbey (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AVRO-1817?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15219902#comment-15219902 ] 

Sean Busbey commented on AVRO-1817:
-----------------------------------

I can't think of anything this would break, and I'm kind of surprised it's not already handled.

Interested in putting up a patch [~movermeyer]?

> Allow enums to be "promoted" to strings
> ---------------------------------------
>
>                 Key: AVRO-1817
>                 URL: https://issues.apache.org/jira/browse/AVRO-1817
>             Project: Avro
>          Issue Type: Improvement
>          Components: java, spec
>            Reporter: Michael Overmeyer
>            Priority: Minor
>
> We should consider adding a resolution rule that can promote an enum to a string using the enum's symbol.
> I have an Avro schema that has a field with an enum type. However, I have realized that an enum is not the type I actually wanted. I would much rather have the type of the field be a string. I went to change this, but of course this type of change (enum -> string) is not within the bounds of Avro's schema evolution. Therefore a reader with this changed schema is not be able to read an object written with the old schema.
> For example, if the writer schema was:
> enum Colour {
>   RED, YELLOW, GREEN 
> }
> protocol stoplight {
>   Colour colour;
> }
> And the reader schema was:
> protocol stoplight {
>   string colour;
> }
> Then when you access the colour field of your object, you get the string representation of the enum value's symbol .
> For example, Colour.RED => "RED", Colour.YELLOW => "YELLOW", Colour.GREEN => "GREEN"



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