confluentinc/schema-registry

`ProtobufConverter`: representing `oneof` fields as unions is inconsistent with other implementations

mdub opened this issue · 3 comments

mdub commented

When faced with a Protobuf schema that uses oneof fields, such as:

message SampleMessage {
  oneof test_oneof {
    string name = 4;
    SubMessage sub_message = 9;
  }
}

the ProtobufConverter generates a union struct. When the resulting SchemaAndValue is serialized, e.g. to JSON, the "oneof field" will be represented in the structure, e.g.

{
  "test_oneof": {
    "name": "Bob Dobbs"
  } 
}

This is inconsistent with most other implementations of Protobuf → JSON serialization, which do not "box" oneof field-sets in this way. For example, println(sampleMessage.toJson()) would typically yield simply:

{
  "name": "Bob Dobbs" 
}
mdub commented

I'm wondering whether the "boxing" behaviour (i.e. generation of a union struct per oneof) could be made configurable, so that we could opt out.

mdub commented

Hi @rayokota. I notice this issue has been closed, but your PR to fix it has not yet been merged. Any update on when it might be merged, and released?

rayokota commented

Sorry, closed prematurely, it will be merged toward the end of Sept

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