How to convert a method that takes an OnError and OnCompleted into an Observable

Question

Hi all, There is probably a really easy answer to this but my brain just isn't working.

I have a method I need to call in a framework that is not Observable aware, that has the following pattern.

client.GetAsync<TResult>(
     string resource, 
     Action<Exception> onError, 
     Action<TResult> onCompleted);

I need to convert this into a synchronous action that waits for the result. I figured Rx would help me so I tried

var observable = Observable.Create<XElement>(
    observer => () => client.GetAsync<XElement>(
        "resource1",
        observer.OnError,
        observer.OnNext);
var result = observable.First();

But this here but this just deadlocks, I tried making it ObserveOn new thread and SubscribeOn new thread. But it still deadlocks, am I even on the right track?

Answer 1

You're on the right track, with a small adjustment.:

var observable = Observable.Create<XElement>( 
    observer => 
    {
        client.GetAsync<XElement>( 
        "resource1", 
        observer.OnError, 
        x => 
        {
           observer.OnNext(x);
           observer.OnCompleted();
        }); 
        return () => {};
    });

Just as a comment, using RX to make synchronous stuff from asynchronous is kinda "goes against the grain". Normally, RX is used to make asynchronous from synchronous or make asynchronous easier.