Chapter143:ReactiveExtensions(Rx)

Section143.1:ObservingTextChangedeventonaTextBox

AnobservableiscreatedfromtheTextChangedeventoftheTextBox.Alsoanyinputisonlyselectedifit’sdifferent from the last input and if there was no input within 0.5 seconds. The output in this example is sent to the console.

Observable

.FromEventPattern(textBoxInput,”TextChanged”)

.Select(s=>((TextBox)s.Sender).Text)

.Throttle(TimeSpan.FromSeconds(0.5))

.DistinctUntilChanged()

.Subscribe(text=>Console.WriteLine(text));

Section143.2:StreamingDatafromDatabasewith Observable

AssumehavingamethodreturningIEnumerable<T>,f.e.

privateIEnumerable<T>GetData()

{

try

{

//returnresultsfromdatabase

}

catch(Exceptionexception)

{

throw;

}

}

Creates an Observable and starts a method asynchronously. SelectManyflattens the collection and the subscription is fired every 200 elements through Buffer.

intbufferSize=200;

Observable

.Start(()=>GetData())

.SelectMany(s=>s)

.Buffer(bufferSize)

.ObserveOn(SynchronizationContext.Current)

.Subscribe(items=>

{

Console.WriteLine(“Loaded{0}elements”,items.Count);

//dosomethingontheUIlikeincrementingaProgressBar

},

()=>Console.WriteLine(“Completedloading”));