protoc-gen-go: support go_tag option to specify custom struct tags

[jedborovik]

Is it possible to define a message with custom tags? For example defining a json name that isn't just the lowercase field name or adding a bson tag.

[dsymonds]

No, there's no support for that, nor any intention to support that.

[mwmahlberg]

I'd like to add that this feature would be extremely useful for validation purposes.

[jswierad]

+1

Use case: Using protobuf generated structs along with sqlx package. Would be awesome

[mikebell-org]

Likewise the go library for cloud datastore. Basically, increasing numbers of things make use of struct tags, and without support for them you're left manually duplicating structs? If there are no plans to add this functionality, what is the recommended way to handle it?

[iain17]

I would love this feature!
This seems to somehow mitigate the need

https://github.com/favadi/protoc-go-inject-tag

[sefasenturk95]

I would love this feature aswell!

[willks]

This would be handy, as I need to validate JSON payloads for my REST API portion of the service.

[awalterschulze]

Since golang/protobuf will probably never support this. Here are some solutions.

https://github.com/mwitkow/go-proto-validators is useful for validation on proto structs.

https://github.com/gogo/protobuf can be used in two ways to have custom tags:

1. You can use the moretags extension
   https://github.com/gogo/protobuf/blob/master/test/tags/tags.proto

2. Or you can use the typedecl extension if you don't want to generate the golang struct.
   This allows you declare your own golang struct with all the tags you want and more.

[ekiyanov]

Need it as well to automate insert/update into the sql database

[qianlnk]

I've add a plugin retag for protoc-gen-go.

https://github.com/qianlnk/protobuf/tree/master/protoc-gen-go/retag

protoc --go_out=plugins=grpc+retag:. yourproto.proto

[RajeshKumar1990]

@qianlnk .thanks.I tried your plugin when i use only message then ther is no problem but when the message have sub message like this

message SendData {
	message MetaData{
		string Name = 1;//`json:"name;omitempty"`
		int64 Length = 2;//`json:"length;omitempty"`
	}
	message Chunck{
	bytes Data = 1;//`json:"data;omitempty"`
	int64 Position = 2;//`json:"position;omitempty"`
	}
}

This throws the error.Any how the retag can support this???
Thanks...

[qianlnk]

@RajeshKumar1990 I fixed it.