/// <summary>
/// Creates a new event-pattern observable which raises on an item updated in the repository.
/// The observable yields:
/// - the Item on the Add/Update action,
/// - the NewItems the a Reset action,
/// - none on the Remove action.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="r"></param>
/// <returns></returns>
public static IObservable <T> ItemUpdated <T>(this IObservableInventory <T> r) where T : IIdentifiable =>
Observable.Create <T>(observer =>
r.Changed.Subscribe(ep =>
{
var action = ep.EventArgs.Action;
if (action == ItemChangedAction.Add || action == ItemChangedAction.Update)
{
observer.OnNext(ep.EventArgs.Item);
}
else if (action == ItemChangedAction.Reset && ep.EventArgs.NewItems != null)
{
foreach (var item in ep.EventArgs.NewItems)
{
observer.OnNext(item);
}
}
}));
/// <summary>
/// Projects <see cref="IObservableInventory{T}"/> to <see cref="IObservableEnumerable{T}"/>.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="r"></param>
/// <returns></returns>
public static IObservableEnumerable <T> AsObservableEnumerable <T>(this IObservableInventory <T> r) where T : IIdentifiable =>
ObservableEnumerable.Create(r.Items, r.ItemUpdated());
