How to create a factory for a typeorm custom repository in nestjs?

Question

I have a repository:

export class MyRepository 
    extends 
        Repository<MyEntity>
{

constructor(
        protected readonly _clientId: string
    ) {
        super()
    }

 // ... methods
}

I need to pass the client id through which isnt known until request time. As such, the only way I know how to do it would be to create a factory which can create the repo at run time (it's in GRPC metadata).

@Injectable()
export class MyRepositoryFactory {
    create(clientId: string) {
        return new MyRepository(
            clientId,
        );
    }
}

I register this as a provider and then in my controller I call:

const { clientId } = context;
const repository = this.myRepositoryFactory.create(clientId);

However I get the error

"Cannot read property 'findOne' of undefined"

when trying to do a basic typeorm call. I can see this is because instead the repository should be registered in the module imports like:

imports: [
    TypeOrmModule.forFeature([ MyRepository, MyEntity ])
  ],

However this only works when injecting the repository directly, not in a factory. I have no idea how to either overcome this problem, or use a different way of creating the repository at run time with GRPC meta data passed through. Any help would be appreciated, thanks.

Answer 1

you cant call new and have the repository connected to TypeORM.
for that you need to make call to getCustomRepository(MyCustomRepository (or connectio.getCustomRepository ) so it would be connected to the connectiong pool and everything TypeORM hides under the hood.

IMO creating a custom repository per request is not such a great idea, maybe you can create a Provider that has scope REQUEST (so the provider would be created per-request) allowing NestJS to inject the repository the 'standard' way, modify it's client attribute and then use it's methods that uses the internal repository methods.
something like

@Injectable({ scope: Scope.REQUEST })
export class RequestRepositoryHandler {
  client_id: string
  
  constructor(@InjectRepository(MyEntity) private repo: Repository<MyEntity>){}

  // other methods
}

// usage
@Injectable()
export class SomeService {
  constructor(private providerRepo: RequestRepositoryHandler){}

  async method(client_id: string){
    this.providerRepo.client_id = client_id; // the provider is per-request
    // now do some work
  }
}