Protobufs: options in .proto files

[Tess Rinearson]

TL;DR: Does golang/protobuf support custom options? 

I’m playing around with generating files from .proto files. We have a service written in JS that uses proto files to generate JS objects, and we want to be able to use the same proto files for our Go services.

I can get golang/protobuf working with the example .proto file, which looks like this: 

package example;

enum FOO { X = 17; };

message Test {

  required string label = 1;

  optional int32 type = 2 [default=77];

  repeated int64 reps = 3;

  optional group OptionalGroup = 4 {

    required string RequiredField = 5;

  }

}

This file doesn’t have any options or field options other than “default,” which is a built-in field option,  I think. (I’m kind of a protobuf noob, so bear with me please.) 

Anyways, our preexisting proto files use options and custom field options, kind of like this: 

package example;

message Vegetable {

  option key = "Vegetable";

  optional string vegetable_id = 1;

  optional string name = 2  [removed=true];

}

When I try to run protoc on that, I get: 

example.proto:7:30: Option "removed" unknown.

example.proto:4:10: Option "key" unknown.

Does that mean that golang/protobuf doesn’t support custom options? 

There’s a line in golang/protobuf that says “TODO: options.” (https://github.com/golang/protobuf/blob/3ea3e05dbfae8d2dd0cc219b5f0f0ba4606d15eb/protoc-gen-go/generator/generator.go#L1424) which makes me think that they’re not supported yet, but I wanted to double check. :) Is this something that the team is already working on? And if not, is that something I (or one of my coworkers) could contribute?

If options are already supported--Is there something else I need to do to add my custom options to get the generator to recognize them?

Or, if they’re not supported and golang/protobuf won’t be able support them anytime soon, does anyone have a good way to add custom options to protos for golang? 

Thank you! 

Tess

[Rob Pike]

They are not supported. There are no plans to support them but that may change.

However, your example looks more like user error. The message is coming from protoc, not the Go plugin. You're using a custom option that is not defined.

-rob

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[Tess Rinearson]

Oops. Well, that's embarrassing.

Anyways, thanks for pointing that out and also for clarifying the state of custom option support! 

[kwi...@gmail.com]

It seems go doesn't support custom protobuf options still.  Are there any plans for support?