get default values when deserializing protobuf events using parse_proto

[amirongit]

so here's the proto

syntax = "proto3";

package mdm.v1.base;

enum DeviceType {
  MASTER = 0;
  SLAVE = 1;
}

enum CommandType {
  CLOCK = 0;
  ...
}

message Data {
  DeviceType device_type = 1;
  CommandType command_type = 2;
}

and here is the message published in nats: CAAQAQ==; which is equivalent of Data with these values

{
    "device_type": 0,
    "command_type": 1
}

in vector.json configuration, I have a transform with type remap, which uses a simple VRL script to parse proto; this is the script:
. = parse_proto!(decode_base64!(.message), "resource/static/proto/base.desc", "mdm.v1.base.Data")

the problem is that, when the value for the field device_type of Data is 0 (the default value), the resulted won't contain the "device_type" field.

I need to include all the fields in the output of this script. how do I do it? is it possible?

[amirongit]

ps: it's protobuf itself omitting default values.

[pront]

Hi @amirongit,

In your source, after you do:

result = parse_proto!(decode_base64!("<some bytes>"), "resources/protobuf_descriptor_set.desc", "test_protobuf.Person") 

You can use exists and if a field is not present, explicitly set it to the default value.

Long term we can see if a emit_defaults optional argument can be added to parse_proto so that it adds these fields while traversing the proto instances.