Question

I have a listbox which has couple of items. When double clicked on each item, the user get option to edit item (text of item). Now once i update the item, my item in listbox doesn’t get updated.

The first window (one which has listbox) is in MainWindow.xaml file and second window is in EditTaskView.xaml(one which let’s edit the items text) file.

The code that displays items in lists is:

Main.Windows.cs

public static ObservableCollection TaskList;

    public void GetTask()
    {
        TaskList = new ObservableCollection<Task>
                           {
                               new Task("Task1"),
                               new Task("Task2"),
                               new Task("Task3"),
                               new Task("Task4")
                           };

        lstBxTask.ItemsSource = TaskList;
    }

private void lstBxTask_MouseDoubleClick(object sender, MouseButtonEventArgs e)
{

        var selectedTask = (Task)lstBxTask.SelectedItem;
        EditTask.txtBxEditedText.Text = selectedTask.Taskname;
        EditTask.PreviousTaskText = selectedTask.Taskname;  
        EditTask.Visibility = Visibility.Visible;
    } 

The xaml code that displays the list:

<ListBox x:Name="lstBxTask" Style="{StaticResource ListBoxItems}" MouseDoubleClick="lstBxTask_MouseDoubleClick">
        <ListBox.ItemTemplate>              
            <DataTemplate>                   
                <StackPanel>
                    <Rectangle Style="{StaticResource LineBetweenListBox}"/>
                    <StackPanel Orientation="Horizontal">
                        <TextBlock Text="{Binding Taskname}"  Style="{StaticResource TextInListBox}"/>
                        <Button Name="btnDelete" Style="{StaticResource DeleteButton}" Click="btnDelete_Click"/>                                                     
                    </StackPanel>
                </StackPanel>                   
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox> 
    <ToDoTask:EditTaskView x:Name="EditTask" Grid.Row="1" Grid.RowSpan="2" Grid.ColumnSpan="2" Visibility="Collapsed"/> 

The Save button in TaskEditView.xaml does this:

    public string PreviousTaskText { get; set; }

 private void btnSaveEditedText_Click(object sender, RoutedEventArgs e)
 {
            foreach (var t in MainWindow.TaskList)
            {
                if (t.Taskname == PreviousTaskText)
                {
                    t.Taskname = txtBxEditedText.Text;
                }
           }

            Visibility = Visibility.Collapsed;

 }

TaskList is the ObservableCollection, and i though once you update the value the UI gets refreshed. But doesn’t seem to work that way.

What am i missing?

Answer 1

Looks like you may need to implement INotifyPropertyChanged in your Task class. This interface alerts the UI that underlying data has changed and it needs to repull the data to update the view.