コンバーターを使用すると、初めて完全に機能しますが、1 つ以上のログがログ リストに表示された場合、コンバーターは初回のみ機能するため、バインディングは更新されません。項目コントロールではないすべてのコントロールは、listchanged イベントをサブスクライブしません!
ここに、このシナリオの小さなコードがあります
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>
コンバーター
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;
}
}
}
編集
ここに更新の問題の簡単な解決策があります（これは添付プロパティでも作成できます）
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;
}
の使用法は次のとおりですCustomTextBlock（テストされていません）
<TextBlock Text="{Binding Path=ListToBind, RelativeSource=Self, Converter={StaticResource ListToStringConverter}}"
ListToBind={Binding Path=Logs} />
@Fueledこれが役立つことを願っています