Nestjs/microservice does not create an observable? - node.js

Question

I was trying to use streams with grpc.
But when I use the below-published code, it says that subscribe is not a function.
It seems like nestjs/microservice does not create an observable from a stream.
The method used in the docs seems to be outdated.
My code - proto file:
message Rating {
string id = 1;
uint32 value = 2;
string comment = 3;
string type = 4;
}
service RatingsRpcService {
rpc Test (stream GetRatingRequest) returns (stream Rating);
}
message GetRatingRequest {
string id = 1;
}
message Ratings {
repeated Rating items = 1;
}
And the controller file:
#GrpcStreamMethod('RatingsRpcService')
test(msg: Observable<any>, metadata: any): Observable<any> {
const subject = new Subject();
msg.subscribe({
next: (item: any) => {
subject.next({whatever: 'value'});
},
error: (err: any) => console.log(err),
complete: () => subject.complete()
});
return subject.asObservable();
}
And the error I get: TypeError: msg.subscribe is not a function
Did I miss something?

Answer 1

Okay, I guess I found the issue.
It's kinda strange, but changing the type from Observable fixed the error.
I mean this one: messages: any instead of messages: Observable<any> or messages: Observable<RatingInterface>.
Please find the code presented below:
#GrpcStreamMethod('RatingsRpcService')
async findByIdStream(messages: any, metadata: any): Promise<Observable<RatingInterface>> {
const subject = new Subject<RatingInterface>();
messages.subscribe({
next: async (dto: GetRatingDto) => {
const item = await this.ratingsService.findById(dto.id);
subject.next(item);
},
error: (err: any) => {
throw new RpcException('Could not process stream.')
},
complete: () => subject.complete()
});
return subject.asObservable();
}