X: Bind StackOverflow when trying x: Bind ListView.SelectedItem using TwoWay mode

Question

I am trying to bind ListView.SelectedItem with the new x: Bind. My code is:

View:

//MainPage.xaml:

<Page
x:Class="BrokenListSample.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:BrokenListSample"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">

<Grid Background="Beige">
    <Grid.RowDefinitions>
        <RowDefinition></RowDefinition>
        <RowDefinition></RowDefinition>
    </Grid.RowDefinitions>

    <ListView Grid.Row="0" Background="LawnGreen" 
              ItemsSource="{x:Bind ViewModel.MyItems, Mode=OneWay}"
              SelectedItem="{x:Bind ViewModel.BestItem, Mode=TwoWay}"
              Width="300" Height="300"/>

    <ListView Grid.Row="1" Background="LawnGreen" 
              ItemsSource="{Binding MyItems, Mode=OneWay}"
              SelectedItem="{Binding BestItem, Mode=TwoWay}"
              Width="300" Height="300"/>
</Grid>

Code for:

//MainPage.xaml.cs:

using Windows.UI.Xaml.Controls;

namespace BrokenListSample
{
    public sealed partial class MainPage : Page
    {
        public MainPageViewModel ViewModel { get; set; }

        public MainPage()
        {
            InitializeComponent();
            DataContextChanged += (s, e) => { ViewModel = DataContext as MainPageViewModel; };
            DataContext = new MainPageViewModel();
        }
    }
}

and finally ViewModel:

//MainPageViewModel.cs:

using System.Collections.ObjectModel;
using System.ComponentModel;

namespace BrokenListSample
{
    public class MainPageViewModel : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public void OnPropertyChanged(string name)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
        }

        private ObservableCollection<string> _myItems;
        public ObservableCollection<string> MyItems
        {
            get { return _myItems; }
            set { _myItems = value; OnPropertyChanged("MyItems"); }
        }

        private string _bestItem;
        public string BestItem
        {
            get { return _bestItem; }
            set { _bestItem = value; OnPropertyChanged("BestItem"); }
        }

        public MainPageViewModel()
        {
            MyItems = new ObservableCollection<string>() { "One", "Two", "Three", "Four" };
        }
    }
}

As you can see, I have two ListView controls on my MainPage. If you are trying to run this code, comment on one of them depending on what type of binding you want to test. The ListView from the second row uses the old good binding, which just works. There is nothing surprising here.

Surprise comes with one that uses the new x: Bind, which raises a StackOverflowException. Works well with OneWay mode - but TwoWay throws a StackOverflowException whenever I click one of the elements ... hilarious ...

- " ?"

Answer 1

. , , , OnPropertyChanged, ... , :

public string BestItem
{
  get { return _bestItem; }
  set
  {
    if (_bestItem != value)
    {
      _bestItem = value;
      OnPropertyChanged(nameof(BestItem));
    }
  }
}

Answer 2

SelectedItem ListView Object, String, .

, - , IValueConverter -, ,

public class GenericConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, string language)
    {
        return value;
    }

    public object ConvertBack(object value, Type targetType, object parameter, string language)
    {
        // no convert to a specific type needed -> the "value" is already an instance of the correct type.
        return value;
    }
}

x: Bind

<ListView ...
          ItemsSource="{x:Bind ViewModel.MyItems, Mode=OneWay}"
          SelectedItem="{x:Bind ViewModel.BestItem, Mode=TwoWay, 
          Converter={StaticResource GenericConverter}}"
          .../>

App.xaml( ):

<Application
x:Class="Namespace.App"
...
xmlns:Converters="using:Namespace.Converters">
<Application.Resources>
    <ResourceDictionary>
        ...
        <Converters:GenericConverter x:Key="GenericConverter"/>
        ...
    </ResourceDictionary>
</Application.Resources>