It's me again. Questions about injecting service..a rare scenario maybe

[wet hearth]

Can I have a class is doing api stuff, for eg user.api.ts which responsible for calling API

user.api.ts wants to use a helper class user.helper.ts with @Injectable() decorator, should my user.api.ts decorate with @Injectable() too?

I found out if user.api.ts is not with the decorator and trying to inject user.helper.ts, the helper would be undefined in user.api.ts, why?

More context:
user.api.ts

export class UserApi {

}

^ is this wrong? should I decorate it with @Injectable() as well? why? I am not planning to export this class to other modules, it's for internal usage within the modules and it's trying to use some functions from user.helper.ts

user.helper.ts

@Injectable()
export class UserApi {

}

I hope I could get some helps cause I really try to ask a good question in well format, thanks..

[fickle mist]

are your user.api.ts and user.helper.ts in providers array or controllers array of any module?

[gaunt pilot]

Your .api class needs to have @Injectable()

[fickle mist]

unrelated note but like 3 days ago i accidentally find your stack overflow

[wet hearth]

both are included in providers array

[wet hearth]

yup I realised this as well, and I thought I only need to add the decorator if I want to this service to be used by others

cause this api class are not used by any classes but wants to use the helper class

it works this way but why, any framework knowledge behind this?

[gaunt pilot]

There's a PR on the docs repo (nestjs/docs.nestjs.com) on "Advanced Topics" that explains this

[wet hearth]

where shall I find it? I'm on https://github.com/nestjs/docs.nestjs.com

or here https://docs.nestjs.com/

[fickle mist]

Nest.js doc suggest read angular doc about the topic for deep drive in nest.js https://angular.io/guide/dependency-injection