AvroSchemaGenerator: logicalType(s) never set for non-date classes

[credmond]

logicalTypes doesn't appear to be set for anything other than dates.

    public static void main(String[] args) throws Exception {
        // Create AvroMapper and AvroSchemaGenerator
        AvroMapper avroMapper = AvroMapper.builder().addModule(new AvroJavaTimeModule()).build();

        AvroSchemaGenerator schemaGen = new AvroSchemaGenerator();
        schemaGen.enableLogicalTypes(); // Enable logical types

        // Configure AvroMapper with the generator
        avroMapper.acceptJsonFormatVisitor(MyClass.class, schemaGen);

        // Get the generated schema
        Schema schema = schemaGen.getGeneratedSchema().getAvroSchema();

        // Print the schema
        System.out.println(schema.toString(true));
    }

Output:

{
  "type" : "record",
  "name" : "MyClass",
  "namespace" : "com.fasterxml.jackson.dataformat.avro.jsr310",
  "fields" : [ {
    "name" : "someBigDecimal",
    "type" : [ "null", {
      "type" : "string",
      "java-class" : "java.math.BigDecimal"
    } ]
  }, {
    "name" : "someDouble",
    "type" : {
      "type" : "double",
      "java-class" : "java.lang.Double"
    }
  }, {
    "name" : "someDoubleObject",
    "type" : [ "null", {
      "type" : "double",
      "java-class" : "java.lang.Double"
    } ]
  }, {
    "name" : "timestamp",
    "type" : [ "null", {
      "type" : "long",
      "logicalType" : "timestamp-millis"
    } ]
  } ]
}

MyClass:

public class MyClass {
    private Instant timestamp;
    private double someDouble;
    private Double someDoubleObject;
    private BigDecimal someBigDecimal;

    // Setters / getters
}

[cowtowncoder]

This is probably the state of things: logical type support was added a while ago via #283 and that's probably the extent.

Which other types would make sense?

As usual, PRs woud be welcome -- while I likely don't have time to work on this myself, I try my best to help anyone who wants to contribute.

[credmond]

Hi -- actually I thought maybe it was a bug because there's even older closed issues/conversations about this, around 2018. I couldn't quite make sense of it but it seemed like it had been added in the past.

#133

Ends with "I think this is probably obsoleted by later work, closing.".

The other types that would make sense are "decimal" and "uuid" (there may be more as per spec, but I don't think so).

[cowtowncoder]

@credmond My recollection (which may be incomplete for sure) is that date/time types were added but not much else. Adding more types should be straight-forward by someone digging in code (with guidance from earlier work, mainly #283).
I really think it's just omission, original contributor just needed certain types.
And I think Avro spec may have been updated too (although granted "decimal" and "uuid" were probably already mentioned).

Thank you for reporting omission in any case.

[cowtowncoder]

Ok yes, looking bit deeper, #133 would have added support for BigDecimal and UUID. But #283 did not, so there is a gap (latter is a subset of types former would have added). What it would have added (that seems useful) is @AvroType annotation, as well.

To add support, one place to look is where tests are, under com.fasterxml.jackson.dataformat.avro.schema.

[cowtowncoder]

Note: open issues wrt logical types:

• Unable to map the avro data to the POJO  #221
• Incorrect serialization for LogicalType.Decimal (Java BigDecimal) #308

[cowtowncoder]

Sort of related: #536 will add support for java.util.UUID wrt Avro Logical Types.

[cowtowncoder]

Fixed via #542.