C# WPF DataGrid旧编辑元素导致问题

WPF数据网格（.NET 4.5.1）不会自动销毁旧的编辑元素。考虑下面的小例子：

XAML：

    <Window ....
    xmlns:wa="clr-namespace:WpfApplication1">
    ....
    <DataGrid Name="dataGrid" AutoGenerateColumns="False" Height="200" CanUserAddRows="False">
        <DataGrid.Columns>
            <DataGridTemplateColumn Header="testCol">
                <DataGridTemplateColumn.CellTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding TestText}" />
                    </DataTemplate>
                </DataGridTemplateColumn.CellTemplate>

                <DataGridTemplateColumn.CellEditingTemplate>
                    <DataTemplate>
                        <wa:MyTextBox Text="{Binding TestText}" />
                    </DataTemplate>
                </DataGridTemplateColumn.CellEditingTemplate>
            </DataGridTemplateColumn>
        </DataGrid.Columns>
    </DataGrid>

再重复一遍，您将看到多个旧的编辑元素不断触发TextChanged事件

这给我带来了问题，因为我有两列-

Amount

和

AmountUnit

Amount

的编辑元素有一个NumericUpDown，而

AmountUnit

将指定NumericUpDown的小数位数。当然，NumericUpDown有一个强制值方法，该方法将值约束到指定的小数位数。问题是，所有旧的NumericUpDown编辑元素都在相互重叠并重新写入

Amount

值，而此时它们应该被垃圾收集

所以我的问题是，如何在单元格完成编辑后立即销毁或垃圾收集旧的编辑元素？或者这个问题的（简单的）解决方法是什么？

我想出来了：）

问题是DataGridTemplateColumn在其元素卸载后不会自动清除其绑定。也许，因为您可以定义非常复杂的元素，而自动执行将非常困难和耗时

通过反射器查看DataGridTextColumn，我得出结论，我必须手动执行此操作，因为DataGridTextColumn还可以在内部清除绑定

我现在面临的问题是，清除绑定的标准方法都不起作用：

// For instance, I Added a MyTextBox_Unloaded event handler and tried calling:
private void MyTextBox_Unloaded(object sender, RoutedEventArgs e)
{
    // none of these worked
    (sender as MyTextBox).ClearValue(MyTextBox.TextProperty); // this is what DataGridTextColumn internally uses
    BindingOperations.ClearAllBindings((sender as MyTextBox));
    (sender as MyTextBox).SetValue(MyTextBox.TextProperty, null);
    (sender as MyTextBox).Text = null;
    BindingOperations.ClearBinding((sender as MyTextBox), MyTextBox.TextProperty);
}

// I also tried, this:
private void dataGrid_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
{
     var cp = e.EditingElement as ContentPresenter;
     var child = (VisualTreeHelper.GetChild(cp, 0) as UIElement);
     BindingOperations.ClearBinding(cp.BindingGroup.BindingExpressions[0].Target, cp.BindingGroup.BindingExpressions[0].TargetProperty);
     (child as MyTextBox).ClearValue(MyTextBox.TextProperty);
     BindingOperations.ClearAllBindings(child as MyTextBox);
     cp.BindingGroup.BindingExpressions.Clear();
}

但最后我偶然发现了这一点，它确实起了作用：

private void dataGrid_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
{
    if (e.Column is DataGridTemplateColumn)
    {
        BindingOperations.ClearAllBindings(e.EditingElement as ContentPresenter);
    }
}

---

我花了几个小时解决一个问题，然后发现我错过了这一行

var child=（visualtreeheloper.GetChild（cp，0）作为UIElement）
// For instance, I Added a MyTextBox_Unloaded event handler and tried calling:
private void MyTextBox_Unloaded(object sender, RoutedEventArgs e)
{
    // none of these worked
    (sender as MyTextBox).ClearValue(MyTextBox.TextProperty); // this is what DataGridTextColumn internally uses
    BindingOperations.ClearAllBindings((sender as MyTextBox));
    (sender as MyTextBox).SetValue(MyTextBox.TextProperty, null);
    (sender as MyTextBox).Text = null;
    BindingOperations.ClearBinding((sender as MyTextBox), MyTextBox.TextProperty);
}

// I also tried, this:
private void dataGrid_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
{
     var cp = e.EditingElement as ContentPresenter;
     var child = (VisualTreeHelper.GetChild(cp, 0) as UIElement);
     BindingOperations.ClearBinding(cp.BindingGroup.BindingExpressions[0].Target, cp.BindingGroup.BindingExpressions[0].TargetProperty);
     (child as MyTextBox).ClearValue(MyTextBox.TextProperty);
     BindingOperations.ClearAllBindings(child as MyTextBox);
     cp.BindingGroup.BindingExpressions.Clear();
}

private void dataGrid_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
{
    if (e.Column is DataGridTemplateColumn)
    {
        BindingOperations.ClearAllBindings(e.EditingElement as ContentPresenter);
    }
}