Get client stream method return

[jucrouzet]

When using a client stream method like :

    rpc TestClientStream(stream visitons.backend.api.messages.String) returns (visitons.backend.api.messages.String);

How can I use the client to receive the returned value ?

RequestStream only offer the two following methods :

    on(type: 'end', handler: (status?: Status) => void): IRequestStream<T>;
    on(type: 'status', handler: (status: Status) => void): IRequestStream<T>;

none of them contains the returned value.

The returned value is returned like that (in Golang) :

	return stream.SendAndClose(&messages.String{
		String_: fmt.Sprintf("%d messages", count),
	})

[johanbrandhorst]

You can see examples of how to use the streaming methods in the tests: https://github.com/improbable-eng/grpc-web/blob/master/integration_test/ts/src/client.websocket.spec.ts. I think you want to use onMessage.

[jucrouzet]

Ok, thank you for this message, I understand the problem, and it seems to be in improbable-eng/ts-protoc-gen, not grpc-web.

For the method

    rpc TestClientStream(stream visitons.backend.api.messages.String) returns (visitons.backend.api.messages.String);

The js generated is :

APIClient.prototype.testClientStream = function testClientStream(metadata) {
  var listeners = {
    end: [],
    status: []
  };
  var client = grpc.client(API.TestClientStream, {
    host: this.serviceHost,
    metadata: metadata,
    transport: this.options.transport
  });
  client.onEnd(function (status, statusMessage, trailers) {
    listeners.status.forEach(function (handler) {
      handler({ code: status, details: statusMessage, metadata: trailers });
    });
    listeners.end.forEach(function (handler) {
      handler({ code: status, details: statusMessage, metadata: trailers });
    });
    listeners = null;
  });
  return {
    on: function (type, handler) {
      listeners[type].push(handler);
      return this;
    },
    write: function (requestMessage) {
      if (!client.started) {
        client.start(metadata);
      }
      client.send(requestMessage);
      return this;
    },
    end: function () {
      client.finishSend();
    },
    cancel: function () {
      listeners = null;
      client.close();
    }
  };
};

And the TS definition :

interface RequestStream<T> {
  write(message: T): RequestStream<T>;
  end(): void;
  cancel(): void;
  on(type: 'end', handler: (status?: Status) => void): RequestStream<T>;
  on(type: 'status', handler: (status: Status) => void): RequestStream<T>;
}

As you can see, onMessage is not handled.
I will create an issue there, thanks for your time.

[jucrouzet]

Now fixed in improbable-eng/ts-protoc-gen#264