How to use camelCase JSON tags for marshaling structs in gRPC generated files in Go?

user_10345964 0
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take the struct below as an example,

type Foo struct {
    state         protoimpl.MessageState
    sizeCache     protoimpl.SizeCache
    unknownFields protoimpl.UnknownFields

    IsBar         bool            `protobuf:"varint,1,opt,name=is_bar,json=isBar,proto3" json:"is_bar,omitempty"`

IsBar has two JSON tags. When I'm trying to json.Marshal, the second tag is used, which is snake_case, but I prefer to use camelCase one. How is it possible?

protoc protobuf-go grpc go json
2 Answers

using protojson package to marshal your proto.Message

import(
  "google.golang.org/protobuf/encoding/protojson"
  "google.golang.org/protobuf/proto"
)

func Marshal(m proto.Message)([]byte,error){
   return (protojson.MarshalOptions{}).Marshal(m)
}
user_177791940

Or try the gofaster. It's a protoc plugin alternative protoc-gen-go. It support the field extension gogoproto.jsontag which let you custome json tag.

syntax = "proto3";

package helloworld.v1;

import "google/api/annotations.proto";

import "gogo/protobuf/gogoproto/gogo.proto";

option go_package = "github.com/pigfall/kratos-test/api/helloworld/v1;v1";

// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {
    option (google.api.http) = {
      get: "/helloworld/{name}"
    };
  }
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
  string pre_name =2 [(gogoproto.jsontag)="perName"];
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}
user_177791940
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