[AVRO-1474] C++ resolving decoder doesn't work when reader schema has more fields than writer schema

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.7.6
• Component/s: c++
• Assignee: Thiruvalluvan M. G.
• Reporter: Ramana Suvarapu
• Created: 03/Mar/14 19:27
• Updated: 28/Dec/18 16:25
• Resolved: 29/Jun/14 18:00

Description

When reader schema has more number of fields than writer schema, C++ implementation of resolving decoder is throwing exception "throwing exception "Don't know how to handle excess fields for reader.” with out checking whether fields are optional or fields have default values.

Attached are reader and writer schemas. Record in reader schema has 2 additional fields than writer schema. One field is required field but it has default value and another one is optional field (union of null and string). Since one has default value and another is optional both reader and writer schemas are supposed to be compatible.

{"name": "defaultField", "type": "string", "default": "DEFAULT", "declared":"true"}

,

{"name": "optionalField", "type": ["string", "null"],"declared":"true"}

,

main()
{
avro::ValidSchema readerSchema = load("reader.json");
avro::ValidSchema writerSchema = load("writer.json");
avro::DecoderPtr d = avro::resolvingDecoder(writerSchema, readerSchema,avro::binaryDecoder());
}

But when I tried to create resolving decoder, I am getting "Don't know how to handle excess fields for reader.” But Java implementation works.

Also field ordering is not working.

The same issue is reported in AVRO-1360.

Issue Links

• breaks: AVRO-1750 GenericDatum API behavior breaking change