Avro with Java 8 dates as logical type

Question

Latest Avro compiler (1.8.2) generates java sources for dates logical types with Joda-Time based implementations. How can I configure Avro compiler to produce sources that u

Answer 1

You need to create your own Conversions to support java-8 date-time api, below is a conversion for java.time.LocalDate:

class Java8LocalDateConversion extends Conversion {
    @Override
    public Class getConvertedType() {
        return LocalDate.class;
    }

    @Override
    public String getLogicalTypeName() {
        //      v--- reuse the logical type `date`
        return "date";
    }

    @Override
    // convert LocalDate to Integer
    public Integer toInt(LocalDate value, Schema schema, LogicalType type) {
        return (int) value.toEpochDay();
    }

    @Override
    // parse LocalDate from Integer
    public LocalDate fromInt(Integer value, Schema schema, LogicalType type) {
        return LocalDate.ofEpochDay(value);
    }
}

The logical types can be reused in avro, so you can using the existing date logical type, for example:

Schema schema = LogicalTypes.date().addToSchema(Schema.create(Type.INT));

For the serializing & deserializing you should set the GenericData which will find your own conversion, for example:

//serializing
DatumWriter out = new SpecificDatumWriter<>(schema, data());

// deserializing
DatumReader in = new SpecificDatumReader<>(schema, schema, data());

private SpecificData data() {
    SpecificData it = new SpecificData();
    it.addLogicalTypeConversion(new Java8LocalDateConversion());
    return it;
}

If you don't want to configure the GenericData every time, you can use the global GenericData instead, for example:

//      register the conversion globally ---v
SpecificData.get().addLogicalTypeConversion(new Java8LocalDateConversion());