TypeError when trying to inject request scoped service

[Blacksmoke16]

I ran into an issue similar to #9, but when the service is Request Scoped.

For example, using the existing can inject other providers into the factory test case within Loader.test.ts, but making the service definition like:

@Injectable({ scope: Scope.REQUEST })
class TestService {
  test() {
    return { path: "/path" };
  }
}

Yields:

[Nest] 74692  - 09/25/2025, 8:58:45 PM   ERROR [ExceptionsHandler] TypeError: Receiver must be an instance of class DataloaderFactory
    at DataLoader._batchLoadFn (/Users/george/Downloads/nestjs-dataloader/src/Dataloader.factory.ts:19:18)
    at dispatchBatch (/Users/george/Downloads/nestjs-dataloader/node_modules/dataloader/index.js:288:27)
    at /Users/george/Downloads/nestjs-dataloader/node_modules/dataloader/index.js:268:5
    at processTicksAndRejections (node:internal/process/task_queues:85:11)

[robertrossmann]

@Blacksmoke16 Thanks for reporting this. I can reproduce the problem. However, I have not been yet able to pinpoint the reason why the problem is happening. Something somewhere changes how the dataloader is used and it breaks the internal this reference inside the dataloader resolution function. 🤯

I will continue to investigate. I did notice, however, that when I change the controller to be request-scoped and keep the service global it works, perhaps this would work for you in the meantime.

[robertrossmann]

I have found out that for request-scoped services, Nest does not call the class constructor when creating a new instance of the service which in turn leaves private class fields uninitialised and unusable and any attempt to access them leads to exactly your error: TypeError: Receiver must be an instance of class X. This project keeps the resolver function in a private class field.

This is a bug in Nest.js. At this time I do not have time to create a bug report, I will try to submit one sometime by the end of next week. In the meantime, if you have time to report this to Nest.js team please feel free to do so and reference this issue there. 🙏