JSON decoder for AVRO that infers default values. Based on org.apache.avro.io.JsonDecoder from AVRO 1.8.2 and org.apache.avro.io.ExtendedJsonDecoder by zolyfarkas.
Given this schema (in AVRO IDL)
record User {
string username;
union {null, string} name = null;
}
this record is valid and will be decoded properly
{"username":"user1","name":null}whereas this record
{"username":"user1"}will produce something like
org.apache.avro.AvroTypeException: Expected field name not found: name
at org.apache.avro.io.JsonDecoder.doAction(JsonDecoder.java:495)
at org.apache.avro.io.parsing.Parser.advance(Parser.java:88)
at org.apache.avro.io.JsonDecoder.advance(JsonDecoder.java:157)
at org.apache.avro.io.JsonDecoder.readIndex(JsonDecoder.java:447)
...
or
org.apache.avro.AvroTypeException: Expected start-union. Got END_OBJECT
at org.apache.avro.io.JsonDecoder.error(JsonDecoder.java:698)
at org.apache.avro.io.JsonDecoder.readIndex(JsonDecoder.java:441)
at org.apache.avro.io.ResolvingDecoder.doAction(ResolvingDecoder.java:290)
at org.apache.avro.io.parsing.Parser.advance(Parser.java:88)
...
The decoder allows decoding JSON that doesn't specify optional values, provided they have defaults.
Replace
Decoder decoder = DecoderFactory.get().jsonDecoder(SCHEMA, INPUT_STREAM_OR_STRING);with
Decoder decoder = new ExtendedJsonDecoder(SCHEMA, INPUT_STREAM_OR_STRING);and pass it to your reader, as usual:
SpecificDatumReader<T> reader = new SpecificDatumReader<>(SCHEMA_OR_CLASS);
reader.read(null, decoder);