Linking WPF text block to list <string>

If you use the converter it works perfect the first time, but if one or more logs are logged, there is no update to your binding because the converter only works the first time. all controls that do not control items do not subscribe to the event changed in the list!

here is a little code for this scenario

using System;
using System.Collections.ObjectModel;
using System.Windows;

namespace BindListToTextBlock
{
  /// <summary>
  /// Interaction logic for MainWindow.xaml
  /// </summary>
  public partial class MainWindow : Window
  {
    private WorkItem workItem;

    public MainWindow() {
      this.WorkItems = new ObservableCollection<WorkItem>();
      this.DataContext = this;
      this.InitializeComponent();
    }

    public class WorkItem
    {
      public WorkItem() {
        this.Logs = new ObservableCollection<string>();
      }

      public string Name { get; set; }
      public ObservableCollection<string> Logs { get; private set; }
    }

    public ObservableCollection<WorkItem> WorkItems { get; set; }

    private void Button_Click(object sender, RoutedEventArgs e) {
      this.workItem = new WorkItem() {Name = string.Format("new item at {0}", DateTime.Now)};
      this.workItem.Logs.Add("first log");
      this.WorkItems.Add(this.workItem);
    }

    private void Button_Click_1(object sender, RoutedEventArgs e) {
      if (this.workItem != null) {
        this.workItem.Logs.Add(string.Format("more log {0}", DateTime.Now));
      }
    }
  }
}

      

        
        
        
      

    

xaml

<Window x:Class="BindListToTextBlock.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:BindListToTextBlock="clr-namespace:BindListToTextBlock"
        Title="MainWindow"
        Height="350"
        Width="525">
  <Grid>
    <Grid.Resources>
      <BindListToTextBlock:ListToStringConverter x:Key="ListToStringConverter" />
    </Grid.Resources>
    <Grid.RowDefinitions>
      <RowDefinition Height="Auto" />
      <RowDefinition Height="Auto" />
      <RowDefinition />
    </Grid.RowDefinitions>
    <Button Grid.Row="0"
            Content="Add item..."
            Click="Button_Click" />
    <Button Grid.Row="1"
            Content="Add some log to last item"
            Click="Button_Click_1" />
    <ListView Grid.Row="2"
              ItemsSource="{Binding Path=WorkItems}">
      <ListView.View>
        <GridView>
          <GridViewColumn Header="Name">
            <GridViewColumn.CellTemplate>
              <DataTemplate>
                <TextBlock Text="{Binding Path=Name}" />
              </DataTemplate>
            </GridViewColumn.CellTemplate>
          </GridViewColumn>
          <GridViewColumn Header="Log Message">
            <GridViewColumn.CellTemplate>
              <DataTemplate>
                <TextBlock Text="{Binding Path=Logs, Converter={StaticResource ListToStringConverter}}" />
              </DataTemplate>
            </GridViewColumn.CellTemplate>
          </GridViewColumn>
        </GridView>
      </ListView.View>
    </ListView>
  </Grid>
</Window>

      

        
        
        
      

    

converter

using System;
using System.Collections;
using System.Globalization;
using System.Linq;
using System.Windows;
using System.Windows.Data;

namespace BindListToTextBlock
{
  public class ListToStringConverter : IValueConverter
  {
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
      if (value is IEnumerable) {
        return string.Join(Environment.NewLine, ((IEnumerable)value).OfType<string>().ToArray());
      }
      return "no messages yet";
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) {
      return DependencyProperty.UnsetValue;
    }
  }
}

      

        
        
        
      

    

EDIT

here is a quick solution for scrolling updates (this can be done with the attached property too)

public class CustomTextBlock : TextBlock, INotifyPropertyChanged
{
  public static readonly DependencyProperty ListToBindProperty =
    DependencyProperty.Register("ListToBind", typeof(IBindingList), typeof(CustomTextBlock), new PropertyMetadata(null, ListToBindPropertyChangedCallback));

  private static void ListToBindPropertyChangedCallback(DependencyObject o, DependencyPropertyChangedEventArgs e)
  {
    var customTextBlock = o as CustomTextBlock;
    if (customTextBlock != null && e.NewValue != e.OldValue) {
      var oldList = e.OldValue as IBindingList;
      if (oldList != null) {
        oldList.ListChanged -= customTextBlock.BindingListChanged;
      }
      var newList = e.NewValue as IBindingList;
      if (newList != null) {
        newList.ListChanged += customTextBlock.BindingListChanged;
      }
    }
  }

  private void BindingListChanged(object sender, ListChangedEventArgs e)
  {
    this.RaisePropertyChanged("ListToBind");
  }

  public IBindingList ListToBind
  {
    get { return (IBindingList)this.GetValue(ListToBindProperty); }
    set { this.SetValue(ListToBindProperty, value); }
  }

  private void RaisePropertyChanged(string propName)
  {
    var eh = this.PropertyChanged;
    if (eh != null) {
      eh(this, new PropertyChangedEventArgs(propName));
    }
  }

  public event PropertyChangedEventHandler PropertyChanged;
}

      

        
        
        
      

    

used here for CustomTextBlock

(not tested)

<TextBlock Text="{Binding Path=ListToBind, RelativeSource=Self, Converter={StaticResource ListToStringConverter}}"
           ListToBind={Binding Path=Logs} />

      

        
        
        
      

    

@Fueled hope this helps