Problem detect observable OnCompleted in RX - web-services

Question

I have problem with detect onComplited action in RX.
I'm loading data to ListBox from web service.
Basic situation is working great: - "Complited item" is on bottom
App.ViewModel.LoadData();
IObservable<WebServiceClass.ItemGetValues> observable = App.ViewModel.Items
.ToObservable(Scheduler.NewThread);
var items = new ObservableCollection<WebServiceClass.ItemGetValues>();
ListBox1.ItemsSource = items;
observable.ObserveOnDispatcher().Subscribe(
item => { items.Add( new WebServiceClass.ItemGetValues(item.nazwa, item.skrot, item.id) ); },
() => { items.Add( new WebServiceClass.ItemGetValues("Complited", "", "") ); }
);
But when I call web service for each item with code below the "Complited item" is added at first
App.ViewModel.LoadData();
IObservable<WebServiceClass.ItemGetValues> observable = App.ViewModel.Items
.ToObservable(Scheduler.NewThread);
var items = new ObservableCollection<WebServiceClass.ItemGetValues>();
ListBox1.ItemsSource = items;
observable.ObserveOnDispatcher().Subscribe
(item =>
{
//items.Add(item);
var request = Observable.FromAsyncPattern<string, string>(client.BeginGetLastValue, client.EndGetLastValue);
request(item.skrot).ObserveOnDispatcher().Subscribe(
(it) =>
{
Func<string, WebServiceClass.ItemGetValues> deserializeFirst = r =>
((List<WebServiceClass.ItemGetValues>)JsonConvert
.DeserializeObject(r,
typeof(List<WebServiceClass.ItemGetValues>)))
.First();
item.zm_dzienna = deserializeFirst(it).zm_dzienna;
items.Add(item);
}
);
},
() => { items.Add(new WebServiceClass.ItemGetValues("Complited", "Complited", "0")); }
);
How can I properly detect onComplited action?
Solution
Problem with nullReference exception in deserializeFirst func.
App.ViewModel.LoadData();
IObservable<WebServiceClass.ItemGetValues> observable = App.ViewModel.Items
.ToObservable(Scheduler.NewThread);
var items = new ObservableCollection<WebServiceClass.ItemGetValues>();
ListBox1.ItemsSource = items;
var request = Observable.FromAsyncPattern<string, string>(client.BeginGetLastValue, client.EndGetLastValue);
observable.SelectMany(
item => request(item.skrot).Select(it => {
Func<string, WebServiceClass.ItemGetValues> deserializeFirst = r =>
((List<WebServiceClass.ItemGetValues>)JsonConvert
.DeserializeObject(r,
typeof(List<WebServiceClass.ItemGetValues>)))
.First();
item.zm_dzienna = deserializeFirst(it).zm_dzienna;
return item;
})
).SubscribeOnDispatcher().Subscribe(
result => { Dispatcher.BeginInvoke(delegate { items.Add(result); }); },
() => { Dispatcher.BeginInvoke(delegate { items.Add(new WebServiceClass.ItemGetValues("c","c","c")); }); }
);
Best regards,
Łukasz

Answer 1

You need to pull the inner query into to Rx sequence, not run it from your subscription. Doing so gives you the power of Rx, of composability and testability. And gets you the results you want.
This is a start towards what is needed.
Func<string, WebServiceClass.ItemGetValues> deserializeFirst = r =>
((List<WebServiceClass.ItemGetValues>)JsonConvert
.DeserializeObject(r,typeof(List<WebServiceClass.ItemGetValues>)))
.First();
var request = Observable.FromAsyncPattern<string, string>(client.BeginGetLastValue,
client.EndGetLastValue);
observable
.SelectMany((item) => request(item.skrot))
.Select((it) => item.zm_dzienna = deserializeFirst(it).zm_dzienna)
.ObserveOnDispatcher()
.Subscribe(
item => items.Add(item),
() => items.Add(new WebServiceClass.ItemGetValues("Complited", "Complited", "0")));