ObservableCollection Example WPF

WPF > Controls  > ObservableCollection

ObservableCollection is a dynamic data collection with automatic notifications when items are added, removed, or updated.


Example: Very simple ObservableCollection

In this example we will create a new class named Person and a list of persons using ObservableCollection. Using a DataGrid we will set only a property ItemsSource.  When press Add button the grid is automatically update. Please also see OnCollectionChanged event in which we can display some status of operations.

XAML:

    <Grid>
        <Label Content="First Name" HorizontalAlignment="Left" Margin="9,0,0,0" VerticalAlignment="Top"/>
        <TextBox x:Name="txtFname" HorizontalAlignment="Left" Height="23" Margin="10,26,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="216"/>
        <Label Content="Last Name" HorizontalAlignment="Left" Margin="10,59,0,0" VerticalAlignment="Top"/>
        <TextBox x:Name="txtLname" HorizontalAlignment="Left" Height="23" Margin="11,85,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="215"/>
        <Button x:Name="btnAdd" Content="Add" HorizontalAlignment="Left" Margin="151,127,0,0" VerticalAlignment="Top" Width="75" Click="btnAdd_Click"/>
        <DataGrid x:Name="dgPerson" HorizontalAlignment="Left" Margin="242,10,0,0" VerticalAlignment="Top" Height="300" Width="552"/>
        <Label x:Name="lblStatus" Content="" HorizontalAlignment="Left" Margin="0,284,0,0" VerticalAlignment="Top" Width="226"/>
    </Grid>
 
C# Code:

    public partial class MainWindow : Window

    {
        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);

        }

    }