Allegro JSON Avro Converter

The JsonAvroConverter class provides methods to convert JSON byte arrays into Avro formats. It supports converting to binary Avro and to Avro GenericData.Record objects. It also handles optional fields (unions) without requiring explicit type wrapping in the JSON and ignores unknown fields not declared in the schema.

Key methods:

• convertToAvro(byte[] jsonBytes, String schema): Returns a byte[] containing the binary Avro data.
• convertToGenericDataRecord(byte[] jsonBytes, Schema schema): Returns an org.apache.avro.generic.GenericData.Record.

import tech.allegro.schema.json2avro.converter.JsonAvroConverter;
import org.apache.avro.generic.GenericData;
import org.apache.avro.Schema;

String schema = "{\"type\":\"record\",\"name\":\"Acme\",\"fields\": [{\"name\": \"username\", \"type\": \"string\"}]}";
String json = "{ \"username\": \"mike\" }";

JsonAvroConverter converter = new JsonAvroConverter();

// conversion to binary Avro
byte[] avro = converter.convertToAvro(json.getBytes(), schema);

// conversion to GenericData.Record
GenericData.Record record = converter.convertToGenericDataRecord(json.getBytes(), new Schema.Parser().parse(schema));

If the library does not support certain Avro types (like specific logical types), you can implement the AvroTypeConverter interface to define custom conversion logic. You can target specific fields by checking the path in the canManage method.

To apply your custom converter, instantiate JsonAvroConverter using a CompositeJsonToAvroReader containing your custom converter.

public class CustomFieldConverter implements AvroTypeConverter {
    @Override
    public Object convert(Schema.Field field, Schema schema, Object jsonValue, Deque<String> path, boolean silently) {
        return "custom-" + jsonValue;
    }

    @Override
    public boolean canManage(Schema schema, Deque<String> path) {
        return "customField".equals(path.getLast());
    }
}

// Usage:
JsonAvroConverter converter = new JsonAvroConverter(new CompositeJsonToAvroReader(new CustomFieldConverter()));