Question

i am using a IObservable to do some loading in the background. i want to specify when this is finished loading. How can i do this only once, instead of every time my data retriver does a yield return? How do I do this?

bool IsLoading = true;
ObservableCollection<MyData> dataList = new
ObservableCollection<MyData>();
DataLoader.RetrieveData().ToObservable(Scheduler.ThreadPool).Select(x => x).ObserverOn(Scheduler.Dispatcher).Subscribe(x => {
    dataList.Add(x);
    IsLoading = false;});

Answer 1

You should look at the Finally extension method, it will do exactly what you want!

bool IsLoading = true;
ObservableCollection<MyData> dataList = new ObservableCollection<MyData>();
DataLoader.RetrieveData()
  .ToObservable(Scheduler.ThreadPool)
  .Select(x => x)
  .ObserverOn(Scheduler.Dispatcher)
  .Finally(() => IsLoading = false)
  .Subscribe(x => dataList.Add(x));

That should execute after the observable sequence is terminated.