子财产的收藏更改事件

Question

I have use the following code snippet for Creating ObservableCollection binded to the DataGrid.

public  class Test:INotifyPropertyChanged
    {

        private string _name;
        public  string Name
        {
            get { return _name; }
            set { _name = value;OnpropertyChanged("Name"); }
        }

        private string _city;
        public  string City
        {
            get { return _city; }
            set
            {
                _city = value;OnpropertyChanged("City");}
        }


        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnpropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                var e = new PropertyChangedEventArgs(propertyName);
                handler(this, e);
            }
        }
        #endregion
    }

class Data:INotifyPropertyChanged
    {

        private int customerID;

        public int CustomerID
        {
            get { return customerID; }
            set { customerID = value; OnpropertyChanged("CustomerID"); }
        }

        private bool isSelected;

        public  bool IsSelected
        {
            get { return isSelected; }
            set { isSelected = value; OnpropertyChanged("IsSelected"); }
        }

        private ObservableCollection<Test> _collection;
        public ObservableCollection<Test> Collection
        {
            get { return _collection; }
            set { _collection = value;OnpropertyChanged("Collection" +
                                                        ""); }
        }
        public event PropertyChangedEventHandler PropertyChanged;

        public void OnpropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                var e = new PropertyChangedEventArgs(propertyName);
                handler(this, e);
            }
        }


    }
class ViewModel:NotificationObject
{
    public ViewModel()
    {
        this.GDCSource = Getsource();
    }

    private ObservableCollection<Data> _gdcsource;

    public ObservableCollection<Data> GDCSource
    {
        get { return _gdcsource; }
        set { _gdcsource = value; RaisePropertyChanged("GDCSource");}
    }




    private ObservableCollection<Data> Getsource()
    {
        ObservableCollection<Data> items = new ObservableCollection<Data>();
        if (items != null)
        {
            items.Add(new Data()
                {
                    IsSelected = true,
                    CustomerID = 1,
                });
            items.Add(new Data()
                {
                    IsSelected = true,
                    CustomerID = 2,
                });
        }
        return items;

    }
}

 public partial class MainWindow : Window
    {

        public MainWindow()
        {
            InitializeComponent();
            ViewModel vmModel = new ViewModel();
            this.datagrid.ItemsSource = vmModel.GDCSource;
            vmModel.GDCSource.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler(GDCSource_CollectionChanged);
        }

        void GDCSource_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
        {
            //Listen the collection changed event for underlying source
        }

        // add the object to the Collection property
        private void Test_OnClick(object sender, RoutedEventArgs e)
        {
            (this.DataContext as ViewModel).GDCSource[0].Collection.Add(new Test() { Name = "Name1", City = "City1" });
            (this.DataContext as ViewModel).GDCSource[0].Collection.Add(new Test() { Name = "Name1", City = "City1" });
            (this.DataContext as ViewModel).GDCSource[0].Collection.Add(new Test() { Name = "Name1", City = "City1" });
        }
    }

It is possible to listen while adding Collection property in any event.

Thanks in advance

Regards, Rajasekar

Answer 1

If you mean you want to register for event that is raised when item is added/deleted in observable collection you should look at CollectionChanged event

ObservableCollection<T>.CollectionChanged Event

Occurs when an item is added, removed, changed, moved, or the entire list is refreshed.

Answer 2

You can extend your own version of ObservableCollection if you want and override the add method,

There you can fire any delegates or whatever you may want to register, the UI will update automatically using ObservableCollection with items added/removed you don't need to do anything for that,