NestJS GRPC Error: call.sendMetadata is not a function - nestjs

Question

I'm trying to send a metadata from the server side gprc using NestJS framework. On the official NestJS guide here: it shows a example of doing the server side grpc metadata:
#Controller()
export class HeroesService {
#GrpcMethod()
findOne(data: HeroById, metadata: Metadata, call: ServerUnaryCall<any>): Hero {
const serverMetadata = new Metadata();
const items = [
{ id: 1, name: 'John' },
{ id: 2, name: 'Doe' },
];
serverMetadata.add('Set-Cookie', 'yummy_cookie=choco');
call.sendMetadata(serverMetadata);
return items.find(({ id }) => id === data.id);
}
}
On my code, I wrote a similar code:
#GrpcMethod('ClinicService', 'GetCustomerClinicNames')
async GetCustomerClinicNames_GRPC(data: CustomerClinicID, call:ServerUnaryCall<Any,Any>) {
const metadata = new Metadata();
const result = await this.clinicService.GetClinicName(Number(data.customer_id));
console.log(result);
metadata.add('context', "Jello")
call.sendMetadata(metadata)
return { response: result};
}
However, it gives me an error says:
[Nest] 53188 - 04/06/2022, 5:17:50 PM ERROR [RpcExceptionsHandler] call.sendMetadata is not a function
TypeError: call.sendMetadata is not a function
at ClinicController.GetCustomerClinicNames_GRPC (C:\Users\Vibrant\Desktop\core-samples\src\clinic\clinic.controller.ts:118:10)
at runMicrotasks (<anonymous>)
at processTicksAndRejections (internal/process/task_queues.js:95:5)
at C:\Users\Vibrant\Desktop\core-samples\node_modules\#nestjs\microservices\context\rpc-proxy.js:11:32
But I think the .sendMetadata is indeed a function. Where am I wrong about this?
For the sendMetadata Function, it is defined as:
export declare type ServerSurfaceCall = {
cancelled: boolean;
readonly metadata: Metadata;
getPeer(): string;
sendMetadata(responseMetadata: Metadata): void;
getDeadline(): Deadline;
} & EventEmitter;
export declare type ServerUnaryCall<RequestType, ResponseType> = ServerSurfaceCall & {
request: RequestType;
};

Answer 1

So apparently you need to keep the metadata parameter in your async GetCustomerClinicNames_GRPC. I tried with and without and it only worked when I had it.
so for example, I tried:
#GrpcMethod('HeroesService', 'FindOne')
findOne(data: any, call: ServerUnaryCall<any, any>): any
and that didn't work, then I tried:
#GrpcMethod('HeroesService', 'FindOne')
findOne(data: any, _metadata: Metadata, call: ServerUnaryCall<any, any>): any
and it worked by doing something like:
#GrpcMethod('HeroesService', 'FindOne')
findOne(data: any, _metadata: Metadata, call: ServerUnaryCall<any, any>): any {
const items = [
{ id: 1, name: 'John' },
{ id: 2, name: 'Doe' },
];
const metadata = new Metadata();
metadata.add('context', 'Jello');
call.sendMetadata(metadata);
return items.find(({ id }) => id === data.id);
}
I'm not sure why though, since we are using named arguments.