Hi everyone! I'm currently working with Coroutines...

# android

[Philippe Boisney]

Hi everyone! I'm currently working with Coroutines, and I'm wondering if it's a good approach to pass a Job to a repository's constructor, especially to access it inside a ViewModel (and being able to cancel it)?

class UserRepository(private val service: GithubService,
                     val job: Job)

class SearchUserViewModel(private val repository: UserRepository): ViewModel() {

    private fun cancelJob() {
        repository.job.cancel()
    }
}

[gildor]

You can use Job as lifecycle handler of course, but what is your use case? Usually repositories shouldn't have any predefined Job, instead code that uses repository should manage lifecyle of request (which suspend function)

[gildor]

Also Job is disposable primitive, and it may be not really good to use it for such use case

[Philippe Boisney]

Thanks for your answer. Actually, I'm using `PageKeyedDataSource`and I'm trying to add a network task inside it using a coroutine: https://gist.github.com/PhilippeBoisney/d55e50649b1d8aab7f2aaff36929bbcd

[kenkyee]

I'd suggest exposing suspending functions from the repo instead...

[Philippe Boisney]

@kenkyee This was my first thought. And I'll return Job from this suspending functions?

[kenkyee]

Return the result... Caller maintains job

[gildor]

+1 to @kenkyee
This is what I meant above, repository just exposes suspend functions, management of lifecyle should happen on side of caller. But even in this case repository still can control lifecycle under the hood (should request be cancelled or continue and cache result)

[gildor]

Returning job/deferred from method is not recommended practice, just return result

[Philippe Boisney]

Thanks both of you @gildor @kenkyee. I implemented your recommendations here: https://gist.github.com/PhilippeBoisney/92ac4c853d5dd090c1ecb4e161564ba9

Everything's ok with this implementation?

[kenkyee]

Seeing a job in any of that code is weird to me.

[Philippe Boisney]

@kenkyee How should I manage the job? Because I have to cancel it when user starts typing.

[Philippe Boisney]

@gildor Do you think my actual implementation is wrong? https://gist.github.com/PhilippeBoisney/92ac4c853d5dd090c1ecb4e161564ba9

[kenkyee]

In your activity or fragment

[Philippe Boisney]

Why not inside the VM ?

[kenkyee]

In VM isn't bad either... It knows about lifecycles

[Philippe Boisney]

Actually, this is what I'm doing. I pass the VM scope (uiScope) to my Datasource and cancel it when VM is destroyed. Aldo, I cancel job launched by Datasource when user starts typing. For now, it does the job pretty well 🙂