WPF中DataGridTemplateColumn内ComboBox绑定双属性类问题

我有一个绑定到DataTable的DataGrid，其中包含一列或多列类型为PropList的列。PropList类包含两个成员：string类型的CurrentValue和List<string>类型的Values。尝试将ComboBox的ItemsSource和SelectedValue绑定到这两个成员，但始终无法成功，已尝试多种方案无效。

相关代码片段 #

1. PropList类定义 #

public class PropList
{
    public string CurrentValue;
    public List<string> Values;

    public PropList(string val, List<string>list)
    {
        CurrentValue = val;
        Values = list;
    }
}

2. 创建DataTable列 #

clm = theTable.Columns.Add("The_Model_List", typeof(PropList));

3. DataGrid_AutoGeneratingColumn事件处理 #

if (e.PropertyType == typeof(PropList))
{
    var col = new PropListDataGridTemplateColumn
    {
        Header = e.PropertyName,
        ColumnName = e.PropertyName,
        CellTemplate = (DataTemplate)FindResource("PropListDataTemplate")
    };
    e.Column = col;
    return;
}

4. 自定义PropListDataGridTemplateColumn #

//as found on stackoverflow
public class PropListDataGridTemplateColumn : DataGridTemplateColumn
{
    public string ColumnName
    {
        get;
        set;
    }
    protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
    {
        // The DataGridTemplateColumn uses ContentPresenter with your DataTemplate.
        var cp = base.GenerateElement(cell, dataItem);
        // Reset the Binding to the specific column. The default binding is to the DataRowView.
        cp.SetBinding(ContentPresenter.ContentProperty, new Binding(this.ColumnName));
        return cp;
    }
    protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
    {
        // The DataGridTemplateColumn uses ContentPresenter with your DataTemplate.
        var cp = base.GenerateElement(cell, dataItem);
        // Reset the Binding to the specific column. The default binding is to the DataRowView.
        cp.SetBinding(ContentPresenter.ContentProperty, new Binding(this.ColumnName));
        return cp;
    }
}

5. XAML资源与DataGrid定义 #

<Window.Resources>
    <ResourceDictionary>
        <DataTemplate x:Key="PropListDataTemplate" DataType="DataRowView">
            <ComboBox HorizontalAlignment="Stretch" VerticalAlignment="Center" Margin="1" 
                          ItemsSource="{Binding Path=Values}" SelectedValue="{Binding Path=CurrentValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"></ComboBox>
        </DataTemplate>
    </ResourceDictionary>
</Window.Resources>
<!-- other stuff -->
<DataGrid x:Name="PropData" Margin="5" ItemsSource="{Binding Path=EntityData, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}" AlternatingRowBackground="AliceBlue" 
      SelectionUnit="Cell" SelectionMode="Extended"  CanUserAddRows="False" CanUserDeleteRows="False" CanUserReorderColumns="False" SelectedItem="{Binding SelectedEntity, UpdateSourceTrigger=PropertyChanged}"
      AutoGeneratingColumn="DataGrid_AutoGeneratingColumn" CellEditEnding="PropData_CellEditEnding"/>

补充说明：DataGrid的ItemsSource绑定到ViewModel中的DataTable（EntityData），PropList类对应的列已正确绑定，但无法将其两个成员绑定到ComboBox的ItemsSource和SelectedItem属性。

问题原因与解决方案 #

1. 将字段改为属性（核心问题） #

WPF数据绑定仅支持绑定到属性，不支持绑定到字段。需将PropList中的字段改为带get/set访问器的属性：

public class PropList
{
    public string CurrentValue { get; set; }
    public List<string> Values { get; set; }

    public PropList(string val, List<string> list)
    {
        CurrentValue = val;
        Values = list;
    }
}

2. 修正DataTemplate的DataType #

DataTemplate当前指定的DataType="DataRowView"不符合实际绑定对象（实际绑定的是PropList实例），需修改为：

<!-- 先在XAML头部添加命名空间，替换为你的PropList所在命名空间 -->
xmlns:local="clr-namespace:YourNamespace"

<DataTemplate x:Key="PropListDataTemplate" DataType="{x:Type local:PropList}">
    <ComboBox HorizontalAlignment="Stretch" VerticalAlignment="Center" Margin="1" 
              ItemsSource="{Binding Path=Values}" 
              SelectedValue="{Binding Path=CurrentValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
</DataTemplate>

3. 修复自定义列的GenerateEditingElement方法 #

GenerateEditingElement方法中错误调用了base.GenerateElement，应改为base.GenerateEditingElement：

protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
{
    var cp = base.GenerateEditingElement(cell, dataItem);
    cp.SetBinding(ContentPresenter.ContentProperty, new Binding(this.ColumnName));
    return cp;
}

4. 可选：实现INotifyPropertyChanged（支持动态更新） #

如果需要在CurrentValue或Values变更时自动更新UI，PropList需实现INotifyPropertyChanged接口：

public class PropList : INotifyPropertyChanged
{
    private string _currentValue;
    public string CurrentValue
    {
        get => _currentValue;
        set
        {
            if (_currentValue != value)
            {
                _currentValue = value;
                OnPropertyChanged(nameof(CurrentValue));
            }
        }
    }

    private List<string> _values;
    public List<string> Values
    {
        get => _values;
        set
        {
            if (_values != value)
            {
                _values = value;
                OnPropertyChanged(nameof(Values));
            }
        }
    }

    public PropList(string val, List<string> list)
    {
        CurrentValue = val;
        Values = list;
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

内容的提问来源于stack exchange，提问作者Jeff Mishler