required field

[oo-work]

message SayRequest{
  required string str1 = 1;
  optional int32 int1 = 2;
}

When I use proto2's required and optional, the code generated by protoc --dart_out=grpc:lib/src/generated -Iprotos .\protos\* is as follows

class SayRequest extends $pb.GeneratedMessage {
  factory SayRequest({
    $core.String? str1,
    $core.int? int1,
  }) {
    final $result = create();
    if (str1 != null) {
      $result.str1 = str1;
    }
    if (int1 != null) {
      $result.int1 = int1;
    }
    return $result;
  }
  SayRequest._() : super();
}

All fields are optional, it does not follow the required as expected

factory SayRequest({
    required String str1,
    int? int1,
  }) 

[esrauchg]

Required in protobuf semantics generally doesn't quite behave that way; it is normal and legal to create an in-memory instance without the required fields set, the notion of required is really only only 'this must be set across the wire'.

Also worth calling out the 'required' is considered a regretted feature of Protobuf and is strongly discouraged for new usages (https://protobuf.dev/best-practices/dos-donts/#add-required), because it is extremely difficult to safely remove the field if you realize you don't need it anymore, and so will unduly constrains you from evolving your schema going forward (and the ability to have predictable behavior when safely evolving your schema over time is the main feature of protobuf).