mongodb/naming enhancement for gogo protobuf generator

main.go

// Protocol Buffers for Go with Gadgets
//
// Copyright (c) 2015, The GoGo Authors. All rights reserved.
// http://github.com/gogo/protobuf
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package main

import (
	"regexp"
	"strings"

	"github.com/gogo/protobuf/gogoproto"
	"github.com/gogo/protobuf/proto"
	"github.com/gogo/protobuf/protoc-gen-gogo/descriptor"
	"github.com/gogo/protobuf/protoc-gen-gogo/generator"
	"github.com/gogo/protobuf/vanity"
	"github.com/gogo/protobuf/vanity/command"
)

// ref https://gist.github.com/stoewer/fbe273b711e6a06315d19552dd4d33e6
var matchFirstCap = regexp.MustCompile("(.)([A-Z][a-z]+)")
var matchAllCap = regexp.MustCompile("([a-z0-9])([A-Z])")

func ToSnakeCase(str string) string {
	snake := matchFirstCap.ReplaceAllString(str, "${1}_${2}")
	snake = matchAllCap.ReplaceAllString(snake, "${1}_${2}")
	return strings.ToLower(snake)
}

func main() {
	req := command.Read()
	files := req.GetProtoFile()
	files = vanity.FilterFiles(files, vanity.NotGoogleProtobufDescriptorProto)

	vanity.ForEachFile(files, vanity.TurnOnMarshalerAll)
	vanity.ForEachFile(files, vanity.TurnOnSizerAll)
	vanity.ForEachFile(files, vanity.TurnOnUnmarshalerAll)

	vanity.ForEachFieldInFilesExcludingExtensions(vanity.OnlyProto2(files), vanity.TurnOffNullableForNativeTypesWithoutDefaultsOnly)
	vanity.ForEachFile(files, vanity.TurnOffGoUnrecognizedAll)
	vanity.ForEachFile(files, vanity.TurnOffGoUnkeyedAll)
	vanity.ForEachFile(files, vanity.TurnOffGoSizecacheAll)

	vanity.ForEachFile(files, vanity.TurnOffGoEnumPrefixAll)
	vanity.ForEachFile(files, vanity.TurnOffGoEnumStringerAll)
	vanity.ForEachFile(files, vanity.TurnOnEnumStringerAll)

	vanity.ForEachFile(files, vanity.TurnOnEqualAll)
	vanity.ForEachFile(files, vanity.TurnOnGoStringAll)
	vanity.ForEachFile(files, vanity.TurnOffGoStringerAll)
	vanity.ForEachFile(files, vanity.TurnOnStringerAll)

	vanity.ForEachFieldInFiles(files, patchField)
	vanity.ForEachFile(files, vanity.TurnOffGoGettersAll)

	resp := command.Generate(req)
	command.Write(resp)
}

func patchField(field *descriptor.FieldDescriptorProto) {
	if field.Name == nil {
		return
	}
	if field.Options == nil {
		field.Options = &descriptor.FieldOptions{}
	}

	jsonName := ToSnakeCase(*field.Name)
	jsonTag := "omitempty"
	if gogoJsonTag := gogoproto.GetJsonTag(field); gogoJsonTag != nil {
		split := strings.Split(*gogoJsonTag, ",")
		jsonName = split[0]
		if len(split) > 1 {
			jsonTag = strings.Join(split[1:], ",")
		}
	}

	if jsonName == "id" && field.TypeName != nil && strings.Contains(*field.TypeName, "types.ObjectID") {
		jsonName = "_id"
	}

	field.JsonName = &jsonName
	jsonTag = jsonName + "," + jsonTag
	moreTags := `bson:"` + jsonName + `,omitempty"`

	if more := gogoproto.GetMoreTags(field); more != nil && len(*more) > 0 {
		if strings.Contains(*more, "bson:") {
			moreTags = *more
		} else {
			moreTags += " " + *more
		}
	}

	if strings.Contains(*field.Name, "_id") {
		customname := generator.CamelCase(strings.Replace(*field.Name, "_id", "ID", 1))
		if err := proto.SetExtension(field.Options, gogoproto.E_Customname, &customname); err != nil {
			panic(err)
		}
	}

	if jsonName == "_id" {
		customname := "ID"
		if err := proto.SetExtension(field.Options, gogoproto.E_Customname, &customname); err != nil {
			panic(err)
		}
	}

	if field.TypeName != nil && strings.Contains(*field.TypeName, "google.protobuf.Timestamp") {
		bv := true
		if err := proto.SetExtension(field.Options, gogoproto.E_Stdtime, &bv); err != nil {
			panic(err)
		}
	}

	if err := proto.SetExtension(field.Options, gogoproto.E_Jsontag, &jsonTag); err != nil {
		panic(err)
	}
	if err := proto.SetExtension(field.Options, gogoproto.E_Moretags, &moreTags); err != nil {
		panic(err)
	}
}

example.proto file

Generated example.pb.go