CollectionChanged muestra

Question

¿Alguien puede señalar un ejemplo donde se implementa CollectionChanged. Estoy usando wpf mvvm light. Intenté googlear, no encontré nada lo suficientemente bueno.

Answer 1

public ObservableCollection<string> Names { get; set; } 

public ViewModel() 
{ 
    names = new ObservableCollection<string>(); 
    Names.CollectionChanged += this.OnCollectionChanged; 
} 

void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e) 
{ 
    //Get the sender observable collection 
    ObservableCollection<string> obsSender = sender as ObservableCollection<string>; 

    List<string> editedOrRemovedItems = new List<string>(); 
    foreach(string newItem in e.NewItems) 
    { 
     editedOrRemovedItems.Add(newItem); 
    } 

    foreach(string oldItem in e.OldItems) 
    { 
     editedOrRemovedItems.Add(oldItem); 
    } 

    //Get the action which raised the collection changed event 
    NotifyCollectionChangedAction action = e.Action; 
} 

Para obtener más información acerca de los NotifyCollectionChangedEventArgs vistazo here.

EDITAR: Debido a que necesita una lista de elementos añadidos/eliminados, modifiqué el código de muestra.

Answer 2

public class Person 
    { 
     public string FirstName { get; set; } 
     public string LastName { get; set; } 

    } 
    private ObservableCollection<Person> persons = new ObservableCollection<Person>(); 


    public MainWindow() 
    { 
     InitializeComponent(); 
     dgPerson.ItemsSource = persons; 
     persons.CollectionChanged += this.OnCollectionChanged; 
    } 


    void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e) 
    { 
     //Get the sender observable collection 
     ObservableCollection<Person> obsSender = sender as ObservableCollection<Person>; 
     NotifyCollectionChangedAction action = e.Action; 
     if (action == NotifyCollectionChangedAction.Add) 
      lblStatus.Content = "New person added"; 
     if (action == NotifyCollectionChangedAction.Remove) 
      lblStatus.Content = "Person deleted"; 
    } 
    private void btnAdd_Click(object sender, RoutedEventArgs e) 
    { 
     Person p = new Person(); 
     p.FirstName = txtFname.Text; 
     p.LastName = txtLname.Text; 

     persons.Add(p); 
    } 

A very simple complete example here