android, how to keep suspend function in the ViewModel running when the Fragment is destroyed (from which a coroutines is launched) - android-fragments

Question

Having a Fragment using ViewModel to get data from the Repository.
the ViewModel:
class MyViewModel: ViewModel() {
private var data: Article? = null
// a suspend function actually behaviors as blocking call with withContext
suspend fun getDataByUUID(uuid: String) : Data {
return data ?: withContext(viewModelScope.coroutineContext + Dispatchers.IO) {
(Repository.getDataByUUID(uuid)
.also { data = it }
}
}
}
In the Fragment it uses viewLifecycleOwner.lifecycleScope.launch{} to call into the ViewModel's suspend function getDataByUUID(uuid: String)
fun fetchData() {
myViewModel?.let {
viewLifecycleOwner.lifecycleScope.launch(Dispatchers.Main) {
val data = it.getArticleByUUID(strUUID)
article?.let {
updateUIWithData(it)
}
}
}
}
In Fragment it has viewLifecycleOwner.lifecycleScope.launch{},
inside the launch{} it will wait the data coming back from the ViewModel's getArticleByUUID() and the do update ui.
It works, but having question about the coroutines scope and job cancelation.
here it has viewLifecycleOwner.lifecycleScop in the fragment. and in the ViewModel it has viewModelScope.
the ViewModel may have longer lifetime (in case of configuration i.e. orientation change), and the fragment may be destroyed - recreated by os but the ViewModel is not destroyed
In that case if the fragment is destroyed and the ViewModel is not, I guess the job in the fragment by viewLifecycleOwner.lifecycleScope.launch{} will be canceled, that is what we want, to cancel the job launched from the fragment.
However, we do want the ViewModel's getArticleByUUID() to continue running in the back ground if the ViewModel is still alive (so the data may getting from remote and ready for use next time).
But will the suspend fun getDataByUUID() in ViewModel will also be canceled as well when the Fragment's launched job is canceled?
Is there a way to let the suspend function in the ViewModel continue and not be canceled when the fragment's job launched by viewLifecycleOwner.lifecycleScop.launch{} is canceled?

Answer 1

But will the suspend fun getDataByUUID() in ViewModel will also be canceled as well when the Fragment's launched job is canceled?
As long as you keep using the viewmodelscope in the view model, the job on your viewmodel will only be cancelled when the viewmodel is destroyed.
withContext(viewModelScope.coroutineContext + Dispatchers.IO)
if you remove the viewModelScope.coroutineContext whenever the fragment is destroyed or the job from the fragment is cancelled your getDataByUUID is going to be cancelled.
You can easily test it yourself if you want. You can make a for with delay, like this:
withContext(Dispatchers.IO) {
for (i in 0..1000) {
Log.d("testeVM", i.toString())
delay(1000)
}