I'm using spring boot v3.0.2 with websockets and faced problem with graphQL subscriptions. The task is pretty simple - notify client when backend entity changes. So, I have EntityChangeNotifier -
@Service
public class EntityChangeNotifier {
private final Collection<Listener<MyEntity>> listeners = new ArrayList<>();
@Override
public void notifyChange(MyEntity entity) {
listeners.forEach(listener -> listener.onEntityChange(entity));
}
@Override
public void registerListener(Listener<T> listener) {
listeners.add(listener);
}
interface Listener<T> {
void onEntityChange(T entity);
}
}
Service class -
@Service
public class Service {
private final MyRepository repository;
private final EntityChangeNotifier entityChangeNotifier;
@Autowired
public Service(MyRepository repository, EntityChangeNotifier entityChangeNotifier) {
this.repository = repository;
this.entityChangeNotifier = entityChangeNotifier;
}
@Transactional
public long saveEntity(MyEntity entity) {
MyEntity saved = repository.save(entity);
entityChangeNotifier.notifyChange(entity);
return saved.getId();
}
and GraphQL mappings -
@Controller
public class Mappings {
private final EntityChangeNotifier entityChangeNotifier;
private final Service service;
@Autowired
public Mappings(Service service, EntityChangeNotifier entityChangeNotifier) {
this.service = service;
this.entityChangeNotifier = entityChangeNotifier;
}
@SubscriptionMapping
public Publisher<MyEntity> changed() {
return Flux.create(fluxSink -> entityChangeNotifier.registerListener(fluxSink::next));
}
@MutationMapping
public Long create() {
return service.saveEntity(new MyEntity(0, "testName"));
}
}
GraphQL schema -
type Mutation {
create: Int!
}
type Subscription {
changed: MyEntity
}
type MyEntity {
id
name
}
The code is very basic, but the problem is it doesn't work. I test it via graphiQL and after saving entity, subscription just ends without any result. As far as I discover, sink is marked as cancelled for some reason. Could you please hint me what is wrong? Btw - when I use cold publisher all works fine. But such code, obviously, doesn't comfort me -
@SubscriptionMapping
public Publisher<MyEntity> test() {
Random random = new Random();
return Flux.interval(Duration.ofSeconds(5))
.map(i -> new MyEntity(0, "name" + random.nextInt()));
}
