protoc-gen-go-tag

README

protoc-gen-go-tag

Generates Go code using a package as a tag rewriter that enhanced protoc-gen-go.

protoc-gen-go-tag Generates Go code using a package as a tag rewriter that enhanced protoc-gen-go.

The file xxx.pb.go is modified by protoc-gen-go based on xxx.proto. It has helpful defaults designed for use with protobuf with custom struct tags.

For example, given this snippet,

apply this proto file

syntax = "proto3";

package pb;

//import "google/protobuf/descriptor.proto";
import "github.com/searKing/golang/tools/cmd/protoc-gen-go-tag/tag/tag.proto";

message Http{
  string protocol = 1;
  string version = 2[json_name = "Url", (google.protobuf.field_tag) = {struct_tag: "validate:\"gte=0,lte=130\""}];;
  Url url = 3[json_name = "Url", (google.protobuf.field_tag) = {struct_tag: "json:\"url_tag,omitempty\""}];
  message Url {
    string scheme = 1[json_name = "Scheme", (google.protobuf.field_tag) = {struct_tag: "json:\"schema_tag,omitempty\""}];
    //  string scheme = 1[json_name = "Scheme"];
  }
}

running this command

# https://github.com/searKing/golang/blob/master/tools/cmd/protoc-gen-go-tag/tag/tag.proto
# `tag.proto` needs to be on the `protoc` include path 
protoc -I . --go-tag_out=paths=source_relative:. *.proto

in the same directory will create the file pill.pb.go, containing

// Code generated by protoc-gen-go. DO NOT EDIT.
// source: tag.proto

package pb

import (
	fmt "fmt"
	proto "github.com/golang/protobuf/proto"
	_ "github.com/searKing/golang/tools/cmd/protoc-gen-go-tag/tag"
	math "math"
)

// Reference imports to suppress errors if they are not otherwise used.
var _ = proto.Marshal
var _ = fmt.Errorf
var _ = math.Inf

// This is a compile-time assertion to ensure that this generated file
// is compatible with the proto package it is being compiled against.
// A compilation error at this line likely means your copy of the
// proto package needs to be updated.
const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package

type Http struct {
	Protocol             string    `protobuf:"bytes,1,opt,name=protocol,proto3" json:"protocol,omitempty"`
	Version              string    `protobuf:"bytes,2,opt,name=version,json=Url,proto3" json:"version,omitempty" validate:"gte=0,lte=130"`
	Url                  *Http_Url `protobuf:"bytes,3,opt,name=url,json=Url,proto3" json:"url_tag,omitempty"`
	XXX_NoUnkeyedLiteral struct{}  `json:"-"`
	XXX_unrecognized     []byte    `json:"-"`
	XXX_sizecache        int32     `json:"-"`
}

func (m *Http) Reset()         { *m = Http{} }
func (m *Http) String() string { return proto.CompactTextString(m) }
func (*Http) ProtoMessage()    {}
func (*Http) Descriptor() ([]byte, []int) {
	return fileDescriptor_27f545bcde37ecb5, []int{0}
}

func (m *Http) XXX_Unmarshal(b []byte) error {
	return xxx_messageInfo_Http.Unmarshal(m, b)
}
func (m *Http) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
	return xxx_messageInfo_Http.Marshal(b, m, deterministic)
}
func (m *Http) XXX_Merge(src proto.Message) {
	xxx_messageInfo_Http.Merge(m, src)
}
func (m *Http) XXX_Size() int {
	return xxx_messageInfo_Http.Size(m)
}
func (m *Http) XXX_DiscardUnknown() {
	xxx_messageInfo_Http.DiscardUnknown(m)
}

var xxx_messageInfo_Http proto.InternalMessageInfo

func (m *Http) GetProtocol() string {
	if m != nil {
		return m.Protocol
	}
	return ""
}

func (m *Http) GetVersion() string {
	if m != nil {
		return m.Version
	}
	return ""
}

func (m *Http) GetUrl() *Http_Url {
	if m != nil {
		return m.Url
	}
	return nil
}

type Http_Url struct {
	Scheme               string   `protobuf:"bytes,1,opt,name=scheme,json=Scheme,proto3" json:"schema_tag,omitempty"`
	XXX_NoUnkeyedLiteral struct{} `json:"-"`
	XXX_unrecognized     []byte   `json:"-"`
	XXX_sizecache        int32    `json:"-"`
}

func (m *Http_Url) Reset()         { *m = Http_Url{} }
func (m *Http_Url) String() string { return proto.CompactTextString(m) }
func (*Http_Url) ProtoMessage()    {}
func (*Http_Url) Descriptor() ([]byte, []int) {
	return fileDescriptor_27f545bcde37ecb5, []int{0, 0}
}

func (m *Http_Url) XXX_Unmarshal(b []byte) error {
	return xxx_messageInfo_Http_Url.Unmarshal(m, b)
}
func (m *Http_Url) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
	return xxx_messageInfo_Http_Url.Marshal(b, m, deterministic)
}
func (m *Http_Url) XXX_Merge(src proto.Message) {
	xxx_messageInfo_Http_Url.Merge(m, src)
}
func (m *Http_Url) XXX_Size() int {
	return xxx_messageInfo_Http_Url.Size(m)
}
func (m *Http_Url) XXX_DiscardUnknown() {
	xxx_messageInfo_Http_Url.DiscardUnknown(m)
}

var xxx_messageInfo_Http_Url proto.InternalMessageInfo

func (m *Http_Url) GetScheme() string {
	if m != nil {
		return m.Scheme
	}
	return ""
}

func init() {
	proto.RegisterType((*Http)(nil), "pb.Http")
	proto.RegisterType((*Http_Url)(nil), "pb.Http.Url")
}

func init() { proto.RegisterFile("tag.proto", fileDescriptor_27f545bcde37ecb5) }

var fileDescriptor_27f545bcde37ecb5 = []byte{
	// 262 bytes of a gzipped FileDescriptorProto
	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x5c, 0x8f, 0x31, 0x4f, 0xc3, 0x30,
	0x10, 0x85, 0x95, 0x16, 0x05, 0x6a, 0x98, 0x32, 0x45, 0x41, 0xd0, 0x92, 0xa9, 0x43, 0x13, 0x17,
	0xca, 0x42, 0xa5, 0x22, 0x54, 0x31, 0x20, 0xb1, 0x15, 0x75, 0x46, 0x4e, 0x6a, 0x5d, 0x83, 0x1c,
	0x9f, 0x65, 0x5f, 0x2a, 0xf1, 0xf7, 0xfa, 0x33, 0x18, 0xfa, 0x5b, 0x50, 0x6d, 0x60, 0x60, 0xb8,
	0xe1, 0xf4, 0xde, 0xf7, 0xee, 0x1e, 0x1b, 0x90, 0x80, 0xd2, 0x58, 0x24, 0x4c, 0x7a, 0xa6, 0xca,
	0x9e, 0xa1, 0xa1, 0x6d, 0x57, 0x95, 0x35, 0xb6, 0xdc, 0x49, 0x61, 0x5f, 0x1b, 0x0d, 0x1c, 0x50,
	0x09, 0x0d, 0x9c, 0x10, 0x95, 0xe3, 0x75, 0xbb, 0xe1, 0xde, 0x5f, 0x17, 0x20, 0x75, 0x01, 0x58,
	0x90, 0x00, 0xfe, 0x33, 0x21, 0x29, 0xff, 0x8a, 0xd8, 0xc9, 0x0b, 0x91, 0x49, 0x32, 0x76, 0x16,
	0xbc, 0xa8, 0xd2, 0x68, 0x14, 0x8d, 0x07, 0xab, 0xbf, 0x3d, 0xb9, 0x67, 0xa7, 0x3b, 0x69, 0x5d,
	0x83, 0x3a, 0xed, 0x1d, 0xa5, 0xe5, 0xf5, 0xfe, 0x30, 0xcc, 0x58, 0xba, 0x13, 0xaa, 0xd9, 0x08,
	0x92, 0xf3, 0x1c, 0x48, 0x2e, 0xa6, 0x13, 0x45, 0x72, 0x71, 0x3b, 0x9b, 0xe6, 0xab, 0xfe, 0xda,
	0xaa, 0xe4, 0x91, 0xf5, 0x3b, 0xab, 0xd2, 0xfe, 0x28, 0x1a, 0x9f, 0xdf, 0x5d, 0x94, 0xa6, 0x2a,
	0x8f, 0x87, 0xca, 0xb5, 0x55, 0xbf, 0xfc, 0x87, 0x43, 0x3d, 0xcf, 0x3b, 0xab, 0xde, 0x49, 0xc0,
	0x04, 0xdb, 0x86, 0x64, 0x6b, 0xe8, 0x33, 0xf0, 0xd9, 0x13, 0xf3, 0x31, 0x0f, 0x2c, 0x76, 0xf5,
	0x56, 0xb6, 0x32, 0xbc, 0xb5, 0xbc, 0xd9, 0x1f, 0x86, 0x57, 0xec, 0x32, 0xb0, 0x5e, 0x11, 0xff,
	0xf1, 0xf8, 0xcd, 0x03, 0x55, 0xec, 0x1b, 0xcc, 0xbe, 0x03, 0x00, 0x00, 0xff, 0xff, 0xaf, 0x2e,
	0x0f, 0x31, 0x3a, 0x01, 0x00, 0x00,
}

Download/Install

The easiest way to install is to run go get -u github.com/searKing/golang/tools/cmd/protoc-gen-go-tag@v1.0.175;go get -u github.com/searKing/golang/tools/cmd/protoc-gen-go-tag . You can also manually git clone the repository to $GOPATH/src/github.com/searKing/golang/tools/cmd/protoc-gen-go-tag .

protoc-gen-go-tag: program not found or is not executable

The protoc compiler expects to find plugins named proto-gen-xxx on the execution $PATH. So first:

export PATH=${PATH}:$(go env GOPATH)/bin

xxx.proto: Tried to write the same file twice.

• The protoc-gen-go-tag rewrites *.pb.go by proto-gen-go already. So use protoc-gen-go-tag instead of protoc-gen-go
• protoc-gen-go is installed by go get -u google.golang.org/protobuf/cmd/protoc-gen-go
• Basically the magical incantation (apart from includes) is the --go-tag_out. That triggers the protoc-gen-go-tag plugin to generate *.pb.go. That's it :)

If you use protoc-gen-go installed by go get -u github.com/golang/protobuf/protoc-gen-go

• github.com/golang/protobuf has been superseded by the google.golang.org/protobuf module
• install protoc-gen-go-tag by go get github.com/searKing/golang/tools/cmd/protoc-gen-go-tag@e27209892e58d3df53c587f1feefb6290af17d85
• protoc -I . --go_out=paths=source_relative:. --go-tag_out=paths=source_relative:. *.proto
• *.pb.go generated by protoc-gen-go will be rewritten by protoc-gen-go-tag

trick: embedded tag.proto into your proto directly, avoid include the tag.proto

• Step 1 replace import "github.com/searKing/golang/tools/cmd/protoc-gen-go-tag/tag/tag.proto"; with code in the tag.proto
• Step 2 replace google.protobuf.field_tag with field_tag

syntax = "proto3";

package pb;

// import "github.com/searKing/golang/tools/cmd/protoc-gen-go-tag/tag/tag.proto";
import "google/protobuf/descriptor.proto";
extend google.protobuf.FieldOptions {
  FieldTag field_tag = 65000;
}
message FieldTag {
  // struct tag.
  string struct_tag = 1;// custom struct tag
  UpdateStrategy update_strategy = 2;// update strategy

  enum UpdateStrategy {
    update = 0;// use custom struct tag to update struct tag generated by proto
    replace = 1;// use custom struct tag to replace struct tag generated by proto
  }
}

message Http{
  string protocol = 1;
  string version = 2[json_name = "Url", (field_tag) = {struct_tag: "validate:\"gte=0,lte=130\""}];;
  Url url = 3[json_name = "Url", (field_tag) = {struct_tag: "json:\"url_tag,omitempty\""}];
  message Url {
    string scheme = 1[json_name = "Scheme", (field_tag) = {struct_tag: "json:\"schema_tag,omitempty\""}];
    //  string scheme = 1[json_name = "Scheme"];
  }
}

Inspiring projects

• protobuf

Documentation

Overview

protoc-gen-go-tag is a plugin for the Google protocol buffer compiler to Generate Go code. Install it by building this program and making it accessible within your PATH with the name:

protoc-gen-go-tag

The 'go' suffix becomes part of the argument for the protocol compiler, such that it can be invoked as:

protoc --go-tag_out=paths=source_relative:. path/to/astFile.proto

This generates Go bindings for the protocol buffer defined by astFile.proto. With that input, the output will be written to:

path/to/astFile.pb.go

See the README and documentation for protocol buffers to learn more:

https://developers.google.com/protocol-buffers/