How to pass data from repository to ViewModel using coroutine

Question

This question gave me a general idea but I'm still struggling.

My fragment -

// Reset email sent observer
viewModel.isEmailSent.observe(viewLifecycleOwner, { flag ->
    onResetMailSent(flag)
})

My ViewModel -

val isMailSent: MutableLiveData<Boolean> = MutableLiveData(false)

isEmailSent = liveData {
                emit(firebaseAuthRepo.sendPasswordResetMail(emailId))
            }

My Repository -

suspend fun sendPasswordResetMail(emailId: String): Boolean {
   firebaseAuth?.sendPasswordResetEmail(emailId)
               ?.addOnCompleteListener {
                if (it.isSuccessful) { }
               }
               ?.addOnFailureListener {

               }
}

question -

1. How do I inform the viewmodel that the repo's 'addOnCompleteListener' or 'addOnFailureListener' has been called? I was thinking of returning a boolean flag but seems like I can't place a 'return' statement inside the listeners.

2. IDE says that the 'suspend' modifier is redundant. Why is that?

Answer 1

You can use suspendCoroutine in this case it will basically work as a hook and you can handle the callback stuff with the Continuation object. We need this because firebaseAuth already runs on a separate thread. Try the method below

suspend fun sendPasswordResetMail(emailId: String): Boolean {
    return withContext(Dispatchers.IO) {
        suspendCoroutine { cont ->
            firebaseAuth?.sendPasswordResetEmail(emailId)
                ?.addOnCompleteListener {
                        cont.resume(it.isSuccessful)
                }
                ?.addOnFailureListener {
                    cont.resumeWithException(it)
                }
        }
    }
}