optional nullable is not working

[yingshaoxo]

Generator version: 1.52.1

https://repo1.maven.org/maven2/io/grpc/protoc-gen-grpc-java/1.52.1/protoc-gen-grpc-java-1.52.1-osx-x86_64.exe

Generate command:

cd .gradle
wget https://repo1.maven.org/maven2/io/grpc/protoc-gen-grpc-java/1.52.1/protoc-gen-grpc-java-1.52.1-osx-x86_64.exe
chmod 777 protoc-gen-grpc-java-1.52.1-osx-x86_64.exe
cd ..

mkdir -p app/src/main/java/generated_grpc

protoc --experimental_allow_proto3_optional --plugin=protoc-gen-grpc-java=.gradle/protoc-gen-grpc-java-1.52.1-osx-x86_64.exe \
--java_out=app/src/main/java --grpc-java_out=app/src/main/java \
--proto_path=../party_protocols/protocols free_map_service.proto

Protocols

syntax = "proto3";
package free_map_service;

option go_package = "./free_map_service";

option java_package = "generated_grpc.free_map_service_grpc";
option java_outer_classname = "free_map_service_grpc_types";

service FreeMapService {
    rpc DeletePlace(DeleteRequest) returns (DeleteResponse);
}

message DeleteRequest {
    int32 location_id = 1;
}

message DeleteResponse {
    optional string error = 1;
    bool success = 2;
}

Kotlin code

    override fun deletePlace(
        request: DeleteRequest?,
        responseObserver: StreamObserver<DeleteResponse?>?
    ) {
        responseObserver?.onNext(DeleteResponse.newBuilder()
            .setError(null).setSuccess(true)
            .build())
        responseObserver?.onCompleted()
    }

Error

As I tested out, if I use setError(""), there would have no error.

But if I use setError(null), error happens.

I also tested --experimental_allow_proto3_optional, not working.

Feb 02, 2023 11:11:50 AM io.grpc.internal.SerializingExecutor run
SEVERE: Exception while executing runnable io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$1HalfClosed@587ff7a5
java.lang.NullPointerException
	at generated_grpc.free_map_service_grpc.free_map_service_grpc_types$DeleteResponse$Builder.setError(free_map_service_grpc_types.java:5740)
	at kotlin_free_map_backend_system.FreeMapService.deletePlace(FreeMapService.kt:32)
	at generated_grpc.free_map_service_grpc.FreeMapServiceGrpc$MethodHandlers.invoke(FreeMapServiceGrpc.java:351)
	at io.grpc.stub.ServerCalls$UnaryServerCallHandler$UnaryServerCallListener.onHalfClose(ServerCalls.java:182)
	at io.grpc.internal.ServerCallImpl$ServerStreamListenerImpl.halfClosed(ServerCallImpl.java:340)
	at io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$1HalfClosed.runInContext(ServerImpl.java:866)
	at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)
	at io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:133)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)

[sanjaypujare]

optional in proto3 does not imply nullable for the equivalent field in the generated Java (or Kotlin) code. Specifically you should not call setError(null) just because it is marked optional.

optional in proto3 means you can check on the receiving side to see if the value was explicitly set as stated in Specifying Field Rules.

[yingshaoxo]

Well, if optional field can't be set to null, then why Java has the concept of null? Idiot Here is the progress of Dart: google/protobuf.dart#790 (comment) According to my experiment, Python, JavaScript, Rust, they all support to set optional field to null or None What do you expect? Want me to test CPP and C as well?

…

On Fri, Feb 3, 2023, 3:20 AM sanjaypujare ***@***.***> wrote: optional in proto3 does not imply nullable for the equivalent field in the generated Java (or Kotlin) code. Specifically you should not call setError(null) just because it is marked optional. optional in proto3 means you can check on the receiving side to see if the value was explicitly set as stated in Specifying Field Rules <https://protobuf.dev/programming-guides/proto3/#specifying-field-rules>. — Reply to this email directly, view it on GitHub <#9868 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AEDE7LNAEN7WEQG7XHWG7GTWVQCI5ANCNFSM6AAAAAAUOP2PFA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[ejona86]

This seems really about the protobuf message codegen, so https://github.com/protocolbuffers/protobuf is the place you'd need to file an issue. (If it is an RPC issue then it is gRPC, if it is a message issue it is protobuf.)