WPF DataGrid绑定到具有自定义类型索引器的对象

Question

我试图将带有索引器的类绑定到DataGrid。这是我的班级：

public class Record : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private readonly ConditionalWeakTable<Column, State> state = 
        new ConditionalWeakTable<Column, State>();

    private string name;

    public string Name
    {
        get { return this.name; }
        set
        {
            if (this.name != value)
            {
                this.name = value;
                this.RaisePropertyChanged("Name");
            }
        }
    }

    [IndexerName("Item")]
    public string this[Column column]
    {
        get { return state.GetOrCreateValue(column).Value; }
        set
        {
            var cl = state.GetOrCreateValue(column);

            if (cl.Value != value)
            {
                cl.Value = value;
                this.RaisePropertyChanged("Item[]");
            }
        }
    }

    protected void RaisePropertyChanged(string propertyName)
    {
        if (this.PropertyChanged != null)
        {
            this.PropertyChanged(
                this, 
                new PropertyChangedEventArgs(propertyName));
        }
    }

    private class State
    {
        private string value;

        public State()
        {
            this.value = string.Empty;
        }

        public string Value
        {
            get { return this.value; }
            set { this.value = value; }
        }
    }
}

public class Column
{
}

这是xaml

<DataGrid ItemsSource="{Binding}" AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridTextColumn Header="Name" Width="200" Binding="{Binding Name}" />
        <DataGridTextColumn x:Name="FirstColumn" Header="First" Width="200" />
        <DataGridTextColumn x:Name="SecondColumn" Header="Second" Width="200" />
    </DataGrid.Columns>
</DataGrid>

以下是

背后的代码

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        var first = new Column();
        var second = new Column();

        this.FirstColumn.Binding = new Binding 
        { 
            Path = new PropertyPath("[(0)]", first) 
        };

        this.SecondColumn.Binding = new Binding 
        { 
            Path = new PropertyPath("[(0)]", second) 
        };

        var record1 = new Record { Name = "test 1" };
        record1[first] = "First test 1";
        record1[second] = "Second test 1";

        var record2 = new Record { Name = "test 2" };
        record2[first] = "First test 2";
        record2[second] = "Second test 2";

        this.DataContext = new ObservableCollection<Record> { record1, record2 };
    }
}

代码实际上正在运行。我可以打开窗口，并按预期填充值。但是当我尝试编辑一个单元格时，它会在BindingGroup.CommitEdit（）中使用NullReferenceException进行缓存。

我也尝试过与TextBox相同的绑定，它运行得很好。

任何想法如何解决？