Help migrating code from earliar version of Rx to new

Question

Dear friends,

I am a novice with Rx and I found this code from a silverlightpluscrm book and I tried to use it but its built on the earliar version of Rx with CoreEx assemblies and Observer dll.

 Observable.FromEvent<LoadCompletedEventArgs>(collection, "LoadCompleted").Subscribe(loadcompleted =>
                {
                    observer.OnNext(loadcompleted.EventArgs);
                });

I tried to migrate it using this code and it didn't show errors and compiles but doesn't work.

 Observable.FromEvent<EventHandler<LoadCompletedEventArgs>, LoadCompletedEventArgs>(c => collection.LoadCompleted += c, c => collection.LoadCompleted -= c).Subscribe(loadcompleted =>
                {
                    observer.OnNext(loadcompleted);
                });

I don't know how I could collect the EventArgs as before. I am sorry if my question is silly.

ys,

Sebastian

Answer 1

Hi Sebastian,

Try Observable.FromEventPattern instead:

Observable.FromEventPattern<LoadCompletedEventArgs>(
	c => collection.LoadCompleted += c, 
	c => collection.LoadCompleted -= c)
	.Subscribe(observer.OnNext);

- Dave

---

http://davesexton.com/blog

Answer 2

Hi Sebastian,

Though I suspect that something else may be wrong if your solution doesn't work.  If my solution doesn't work either then try placing a breakpoint in Subscribe to make sure that observer.OnNext is being called.

- Dave

---

http://davesexton.com/blog

Answer 3

Hi Dave,

Thanks a lot for your warm and quick response ... I tried to use the code yesterday and tried to play around ... but it is displaying this error. I am very new to Rx. I am not sure how all this works and am presently just blindly playing around.

argument: can be converted from "Method group" in "System.IObserver < System.Reactive.EventPattern < System.Data.Services.Client.LoadCompletedEventArgs >

the best match for the overloaded System.IObservable < System.Reactive.EventPattern < System.Data.Services.Client.LoadCompletedEventArgs > >.Subscribe (System.IObserver < System.Reactive.EventPattern < System.Data.Services.Client.LoadCompletedEventArgs > >) method has some invalid arguments.

as translated from bingtranslator from German.

ys,

Sebastian

Answer 4

Hi Sebastian,

Please post your code that calls Subscribe so that we can see what the compiler is complaining about.

- Dave

---

http://davesexton.com/blog

Answer 5

Hi Sebastian,

The problem is probably that the method you're passing to Subscribe doesn't accept the correct parameter type.  As I mentioned previously, please post some code so that we can see what you're doing.

- Dave

---

http://davesexton.com/blog

Answer 6

 public static IObservable<LoadCompletedEventArgs> RxRunQuery<CollectionType>(this DataServiceCollection<CollectionType> collection, IQueryable<CollectionType> query)
        {
            return Observable.Create<LoadCompletedEventArgs>(observer =>
            {

                //Observable.FromEventPattern<LoadCompletedEventArgs>(c => collection.LoadCompleted += c, c => collection.LoadCompleted -= c).Subscribe(observer.OnNext);
                Observable.FromEvent<EventHandler<LoadCompletedEventArgs>, LoadCompletedEventArgs>(c => collection.LoadCompleted += c, c => collection.LoadCompleted -= c).Subscribe(loadcompleted =>
                {
                    observer.OnNext(loadcompleted);
                });

                collection.LoadAsync(query);

                return () => { };
            });

        }

        public static iobservable<bool> loadallpages<collectiontype>(this dataservicecollection<collectiontype> collection, iqueryable<collectiontype> query)
        {
            return observable.create<bool>(observer =>
            {
                observable.fromevent<loadcompletedeventargs>(collection, "loadcompleted").subscribe(loadcompleted =>
                {
                    if (collection.continuation != null)
                        collection.loadnextpartialsetasync();
                    else
                        observer.onnext(true);

                });

                collection.loadasync(query);

                return () => { };
            });

        }

Answer 7

Hi Sebastian,

I think the problem is with the call to Subscribe.  I used the short-hand syntax in my example but I didn't realize that the type of the data changed.  You'll have to change this:

.Subscribe(observer.OnNext)

to this:

.Subscribe(e => observer.OnNext(e.EventArgs))

- Dave

---

http://davesexton.com/blog

Answer 8

There are no errors now.

Thanks a lot Dave for you support. I am ashamed for this delayed reply. I am very grateful for you support. I wish you all the best. I will contribute to this forum once I become capable.