Question

How can I convert System.IObservable<string> to System.IObservable<System.Collections.Generic.List<string>>?

public static IObservable<List<string>> GetUrlList(Uri url) {
  var result = (from request in Observable.Return(GetWebRequest(url, false))
    from response in Observable.FromAsyncPattern<WebResponse>(
    request.BeginGetResponse, request.EndGetResponse)()
      from item in GetUrlCollection(response).ToObservable()
    select item);
  return result;
}

Here the type of the item is “list of string”. I need to convert that to IObservable List of strings. How can I achieve this?

Answer 1

Try this:

public static IObservable<List<string>> GetUrlList(Uri url)
{
    var result = (
        from request in Observable.Return(
            GetWebRequest(url, false))
        from response in Observable.FromAsyncPattern<WebResponse>(
            request.BeginGetResponse, request.EndGetResponse)()
        from item in GetUrlCollection(response)
            .ToObservable()
            .ToArray()
        select item
            .ToList());
    return result;
}

My only concern with this whole approach is that your GetUrlCollection(response) is returning an enumerable. You really should code this to return an observable.