Generating map<K, V> on javascript type issue

[sayjeyhi]

What version of protobuf and what language are you using?
Version: master/v3.18
Language: Javascript

What operating system (Linux, Windows, ...) and version? Linux

What runtime / compiler are you using (e.g., python version or gcc version) Nodejs

What did you do?
Steps to reproduce the behavior:

1. Trying to export type map<K, V> so I created a proto file like this:

message MessageResponse {
  string _id = 1;
  string title = 2;
  bool disabled = 3;
  map<string,string> metadata = 4;
}

2. Converting it using this some commands like this:

protoc -I=/libraries/protos/ /libraries/protos/src/*.proto /libraries/protos/src/**/*.proto --plugin=/libraries/protos/binaries/linux/protoc-gen-grpc-web --js_out=import_style=commonjs,binary:/libraries/protos/build/typescript --grpc-web_out=import_style=typescript,mode=grpcwebtext:/libraries/protos/build/typescript --experimental_allow_proto3_optional

3. What I am getting on .ts files is something like:

export namespace MessageResponse {
  export type AsObject = {
    id: string,
    title: string,
    disabled: boolean,
    metadataMap: Array<[string, string]>,
  }
}

4. Well we can see there is a suffix called Map added to my field name! also the generated type is Array<[string, string]>. but what we were expecting, based on language guide here, where an object of {"k": v, …}, like Record<string, V>

What did you expect to see
An object like: Record<string, string>

What did you see instead?
Array<[string, string]>

[elharo]

https://developers.google.com/protocol-buffers/docs/reference/javascript-generated#map

Why Record<string, string> instead of Map<string, string>? (perhaps obvious to a JavaScript developer) but yes, this looks contrary to the spec.

[sayjeyhi]

Based on spec, Map<K, V> sounds better, and that auto-added Map suffix is annoying! I think it is better to let users name their field names. Like what I have here, for metadata, I don't want to have metadataMap; I have types, and everyone using that generated type will understand the return type of this message.

[dibenede]

Agreed that we could generate a better type here. As far as we can tell, grpc-web is just generating the type reflecting what we do.

In the meantime, if you call getMetadataMap() you should get a Map type back.