public MoviePageViewModel() : base(new MovieCatalog())
{
// Initialise the delete Command object with a source (the page view model itself),
// a target (the aggregated Catalog), and a condition (an item must be selected)
_deleteCommand = new DeleteCommandBase <Movie>(this, Catalog, () => ItemSelected != null);
// Define how to react to changes in item selection
ItemSelectionChanged += ItemSelectionChangedHandler;
// Define how to react to changes in aggregated catalog
Catalog.CatalogChanged += CatalogChangedHandler;
}
public MovieCatalog()
{
// Add some domain objects directly to the Catalog
Create(new Movie("Alien", 1979));
Create(new Movie("Terminator", 1984));
Create(new Movie("Inception", 2010));
Create(new Movie("Se7en", 1995));
Create(new Movie("Arrival", 2016));
// The Catalog also acts as a data wrapper, which is
// why the first argument is also "this"
_deleteCommand = new DeleteCommandBase <Movie>(this, this, () => _itemSelected != null);
// When the Catalog content changes (i.e. when something is deleted,
// call OnPropertyChanged for the All property, so those binding to
// this property are notified of the change.
CatalogChanged += i => OnPropertyChanged(nameof(All));
}