protoc-go-inject-tag

protoc-go-inject-tag

Why?

Golang protobuf doesn't support custom tags to generated structs. This script injects custom tags to generated protobuf files, useful for things like validation struct tags.

Install

• protobuf version 3

  For OS X:

  brew install protobuf
  

• go support for protobuf: go get -u github.com/golang/protobuf/{proto,protoc-gen-go}

• go get github.com/favadi/protoc-go-inject-tag or download the binaries from releases page.

Usage

Add a comment with syntax // @inject_tag: custom_tag:"custom_value" before fields to add custom tag to in .proto files.

Example:

// file: test.proto
syntax = "proto3";

package pb;

message IP {
  // @inject_tag: valid:"ip"
  string Address = 1;
}

For oneof fields, a different syntax needs to be used. Add a comment with syntax // @inject_tag_oneof: subfield_name: custom_tag:"custom_value" for each sub-fields that required a tag.

Example:

// file: test.proto
syntax = "proto3";

package pb;

message IP {
  // @inject_tag_oneof: Foo: validate:"required"
  // @inject_tag_oneof: Bar: validate:"non-zero"
  // @inject_tag: valid:"ip"
  oneof data {
    string Foo = 1;
    uint32 Bar = 2;
    string Baz = 3;
}

Generate with protoc command as normal.

protoc --go_out=. test.proto

Run protoc-go-inject-tag with generated file test.pb.go.

protoc-go-inject-tag -input=./test.pb.go

The custom tags will be injected to test.pb.go.

type IP struct {
	// @inject_tag: valid:"ip"
	Address string `protobuf:"bytes,1,opt,name=Address,json=address" json:"Address,omitempty" valid:"ip"`
}

To skip the tag for the generated XXX_* fields, use -XXX_skip=yaml,xml flag.