Getting "type not supported as root type by protobuf" for serialization of short and UUID types

[eldadru]

Hi,

I'm trying to serialize to following class to protobuf using jackson dataformats:

public class HeaderTest
{
  @JsonProperty("version")
  private short version;
  @JsonProperty("messageId")
  private UUID messageId;


  public HeaderTest(short version, UUID messageId)
  {
    this.messageId = messageId;
    this.version = version;
  }
  public short getVersion() {
    return version;
  }

  public void setVersion(short version) {
    this.version = version;
  }

  public UUID getMessageId() {
    return messageId;
  }

  public void setMessageId(UUID messageId) {
    this.messageId = messageId;
  }
}

With the following code:

ProtobufMapper mapper = new ProtobufMapper();
**ProtobufSchema schemaWrapper = mapper.generateSchemaFor(HeaderTest.class);**
NativeProtobufSchema nativeProtobufSchema = schemaWrapper.getSource();
String asProtofile = nativeProtobufSchema.toString();

The bold line throws this exception:

java.lang.UnsupportedOperationException: 'Integer' type not supported as root type by protobuf

	at com.fasterxml.jackson.dataformat.protobuf.schemagen.ProtoBufSchemaVisitor._throwUnsupported(ProtoBufSchemaVisitor.java:141)
	at com.fasterxml.jackson.dataformat.protobuf.schemagen.ProtoBufSchemaVisitor.expectIntegerFormat(ProtoBufSchemaVisitor.java:112)
	at com.fasterxml.jackson.databind.ser.std.StdSerializer.visitIntFormat(StdSerializer.java:215)
	at com.fasterxml.jackson.databind.ser.std.NumberSerializers$Base.acceptJsonFormatVisitor(NumberSerializers.java:75)
	at com.fasterxml.jackson.databind.ser.std.NumberSerializers$ShortSerializer.acceptJsonFormatVisitor(NumberSerializers.java:103)
	at com.fasterxml.jackson.dataformat.protobuf.schemagen.ProtobuffSchemaHelper.acceptTypeElement(ProtobuffSchemaHelper.java:49)
	at com.fasterxml.jackson.dataformat.protobuf.schemagen.MessageElementVisitor.getDataType(MessageElementVisitor.java:122)
	at com.fasterxml.jackson.dataformat.protobuf.schemagen.MessageElementVisitor.buildFieldElement(MessageElementVisitor.java:86)
	at com.fasterxml.jackson.dataformat.protobuf.schemagen.MessageElementVisitor.optionalProperty(MessageElementVisitor.java:65)
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.depositSchemaProperty(BeanPropertyWriter.java:805)
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.acceptJsonFormatVisitor(BeanSerializerBase.java:833)
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.acceptJsonFormatVisitor(DefaultSerializerProvider.java:580)
	at com.fasterxml.jackson.databind.ObjectMapper.acceptJsonFormatVisitor(ObjectMapper.java:3641)
	at com.fasterxml.jackson.databind.ObjectMapper.acceptJsonFormatVisitor(ObjectMapper.java:3620)
	at com.fasterxml.jackson.dataformat.protobuf.ProtobufMapper.generateSchemaFor(ProtobufMapper.java:95)

Any ideas why I can't serialize those types? I couldn't find any online resource about that issue.

Thanks

[cowtowncoder]

I can't say off-hand what could be causing this. Which version is this with?

[eldadru]

Currently, 2.8.1 but also tried the latest version 2.9.0.pr2

[cowtowncoder]

@eldadru then it probably exists in 2.8.7 too. If easy enough would be nice to double-check, but if not this is fine.

[eldadru]

Sorry, I already refactored the code

[cowtowncoder]

@eldadru that's ok, I should be able to reproduce this easily.

[cowtowncoder]

Yes, I can reproduce this. Should work, not sure yet why it does not.

[cowtowncoder]

Ok. Fixing may take a while since this is part of code I did not write (it's a contribution), and some of the logic is bit difficult to follow. Fix for short is relatively easy (it just needs to be handled like int, basically). And in theory UUID and similar types really should be handled as either String, or, perhaps, byte array (since format supports native binary content).
But for some reason current schema generator is pickier...

[cowtowncoder]

There was a bit bigger issue, but things should work significantly better after fix. Will be in 2.9.0.pr3.

[eldadru]

@cowtowncoder Thanks!

[cowtowncoder]

@eldadru Thank you for reporting this: handling was basically wrong and could only support a small number of primitives, regular POJOs and Lists/arrays. What needed to be added was actual handling of typing as indicated by callbacks, so that (for example) date/time values are indicate as types that they would be encoded in JSON (if written as textual timestamps, then String, if long timestamps, 64-bit and so on).

I suspect there may some other rough edges but I hope these can be located and fixed over time as well.