[AVRO-3188] Avro C++ library doesn't accept JSON without a field for union-type fields with default = null

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 1.10.2
• Component/s: c++

Environment

Debian

• Assignee: Unassigned
• Reporter: Prad Nelluru
• Created: 18/Aug/21 19:25
• Updated: 21/Dec/21 20:30

Description

We have a schema with a record with a union-type field with the "null" type being the first type and with a default value of `null`. When given a JSON datum without that field, decoding fails. I'd expect decoding to succeed with that field being given a value of `null`. Repro unit test to place in CodecTests.cc. (Apologies I can't get the code-formatting directives to work, so the code is a bit jumbled.)

{{static void optionalFieldNotSupported() {
const char *text = "

{\"f1\": true }

";
InputStreamPtr in =
memoryInputStream(reinterpret_cast<const uint8_t *>(text),
::strlen(text));

const char *schemaStr = "{\"type\":\"record\",\"name\":\"r\",\"fields\":["
"

{\"name\":\"f1\", \"type\":\"boolean\"}

,"
"

{\"name\":\"f2\", \"type\":[\"null\", \"long\"], \"default\": null}

"
"]}";
ValidSchema schema = parsing::makeValidSchema(schemaStr);
DecoderPtr d = jsonDecoder(schema);

{ d->init(*in); avro::GenericDatum datum(schema); avro::decode(*d, datum); }

}}}