public BookViewModel(Book book, SubscriptionService subs)
{
Book = book;
ButtonsVisible = false;
// hides buttons when user is not signed-in
subs
.WhenAnyValue(x => x.Subscription) // when users subscribption changes
.Select(s => s != null) // set boolean if not null
.ObserveOn(RxApp.MainThreadScheduler) // observe on UI thread
.Subscribe(Observer.Create <bool>(SetButtonVisibility)); // observe changes in SetButtonVisibility method
// update subscription status by observing users subscription
subs
.WhenAnyValue(x => x.Subscription) // when users subscribption changes
.Where(s => s != null && s.SubscribedBookIds != null) // where user has some existing subscribtions
.Select(s => s.SubscribedBookIds.Contains(this.Book.Id)) // set boolean if subscription contains this book
.ObserveOn(RxApp.MainThreadScheduler) // observe on UI thread
.Subscribe(Observer.Create <bool>(SetSubscription)); // observe changes in SetSubscription method
// subscribe command
Subscribe = ReactiveCommand.CreateFromTask(async() => {
await subs.Add(Book.Id);
});
// unsubscribe command
UnSubscribe = ReactiveCommand.CreateFromTask(async() => {
await subs.Remove(Book.Id);
});
}
