if the message has an optional field with a return value, the proto will attach a same name field with _ prefix. why?

[wang-xiaowu]

Problem description

if the message has an option field with a return value, the proto will attach a same name field with _ prefix. why?

Reproduction steps

• message like this

message Res {
    uint32 code = 1;
    optional string msg = 2;
    string status = 3;
    optional string error = 4;
    optional uint32 count = 5;
}

• server retun
  

• real result client got
  

Environment

• OS name, version and architecture: windows11
• Node version : 16.15
• Node installation method. binary
• If applicable, compiler version [e.g. clang 3.8.0-2ubuntu4]
• Package name and version: 1.10.8

Additional context

[murgatroid99]

This is controlled by the message decoding code on the client. What protobuf implementation are you using on the client?

[wang-xiaowu]

proto3 with @grpc/proto-loader.
this is protoLoaderOptions,

const protoLoaderOptions = {
  keepCase: true,
  longs: String,
  enums: String,
  defaults: true,
  oneofs: true,
};