Exceptions on unions of record types

[dininski]

A schema with a union of record types internally serializes to a WrappedUnion type. When passing an object, which conforms to the Avro schema, the library will throw an error, because of the ambiguity.

Pseudo code would be something like:

Avro schema:

{
  "type": "record",
  "namespace": "co.uk.ovotech",
  "fields": [{
    "name": "ambiguous",
    "type": [{
      "name": "record_1",
      "fields": [{"name": "record_field", "type": "int"}]
    }, {
      "name": "record_2",
      "fields": [{"name": "record_field", "type": "int"}, {"name": "record_2_another_field", "type": "int"}]
    }]
  }]
}

The following json will throw, even though it is valid:

{
"ambiguous": {"record_field": 1, "record_2_another_field": 2}
}

The way to work around this is include the type as a key on the level above, i.e. this will not throw:

{
  "co.uk.ovotech.record_2": {
    "ambiguous": {"record_field": 1, "record_2_another_field": 2}
  }
}

However this is not a 1-to-1 mapping of the actual avro schema.

If this is not considered an issue, I think at least it should be documented (if it isn't already).

[ivank]

Where does it error? When building the types or at runtime? Runtime problems are probably from avsc itself and you can probably raise the issue there?