Support Option of sum types #450
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The type `Option[A]` for any sum type `A` should be supported. Right now this fails with `org.apache.avro.AvroRuntimeException: Nested union` (see fd4s#442 problem 1). This is because `Codec[Option[_]]` is build from a `UnionCodec`. We solve the problem by creating a special `Codec` for `Option`s.
erikvanoosten
changed the title
There was mostly a problem in the decoder, not in the encoder. There are still some failing tests but those are just error string mismatches. I will work on that next.
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@bplommer this is ready for review now |
erikvanoosten
changed the title
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Hi, thanks for this and sorry for the long silence! This looks good, but I'd like to try and solve it in a more generic way by making the union codec flatten nested unions in the schema. So I'm going to leave this open for now. |
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Adapting the union codec was also my first attempt. I had a hard time aligning all the types. When I switched to this approach all went pretty smooth. |
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I came up with something but it’s not quite as robust because of the way the union codec uses heuristics in decoding, so I’m going to merge this as a special case. Thanks! |
bplommer
approved these changes
Jul 16, 2022
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The type
Option[A]for any sum typeAshould be supported. Right now this fails withorg.apache.avro.AvroRuntimeException: Nested union(see #442 problem 1).This is because
Codec[Option[_]]is build from aUnionCodecwhich references a nestedUnionCodec. We solve the problem by creating a specialCodecforOptions.