WPF：如何找到所有绑定关系

Question

在我的TextBoxs中，我绑定到dataRowView。我的约束关系是：

TextBox --binding-- DataRowView

或

TextBox --binding-- Property --binding-- DataRowView

有时候我不会直接创建TextBox和DataRowView。

我需要在TextBox中设置MaxLength。 在TextBox中使用WPF TextBox MaxLength -- Is there any way to bind this to the Data Validation Max Length on the bound field?设置MaxLength的第一个关系 但我发现了第二关系的问题。当我将TextBox绑定到属性和属性到DataRowView时，我不知道是什么找到了datarowView。

简单代码 - xaml：

<Window.Resources>
    <l:Behaviors x:Key="BehaviorsStringInput" x:Shared="False">
        <l:RestrictStringInputBehavior/>
    </l:Behaviors>
    <Style x:Key="tb" TargetType="{x:Type TextBox}">
        <Setter Property="l:SupplementaryInteraction.Behaviors" Value="StaticResource BehaviorsStringInput}"/>
    </Style>
</Window.Resources>
<StackPanel Orientation="Vertical">        
    <TextBox x:Name="tb1" Text="{Binding ElementName=_this,Path=MyText}" Width="300" Height="20" Margin="10" Style="{StaticResource tb}"/>
    <TextBox x:Name="tb2" Width="300" Height="20" Margin="10"/>
</StackPanel>

CS：

private DataRowView dr;
public static readonly DependencyProperty MyTextProperty;   
//    
//...
//
    Binding bin = new Binding("TextValue");
    bin.Source = dr;
    bin.Mode = BindingMode.TwoWay;
    tb.SetBinding(TextBox.TextProperty, bin);

    Binding bin2 = new Binding("TextValue");
    bin2.Source = dr;
    bin2.Mode = BindingMode.TwoWay;
    this.SetBinding(MainWindow.MyTextProperty, bin);

RestrictStringInput：

public class RestrictStringInputBehavior : Behavior<TextBox>
{
    protected override void OnAttached()
    {
        AssociatedObject.Loaded += (sender, args) => setmaxlength();
        base.OnAttached();
    }
    private void setmaxlength()
    {
        object context = AssociatedObject.DataContext;
        BindingExpression binding = AssociatedObject.GetBindingExpression(TextBox.TextProperty);            
        if (context != null && binding != null)
        {
            if (context is DataRowView)
            {
                DataRowView drv = (DataRowView)context;
                // bingin.ParentBinding.Path.Path for tb1 has TextValue value and is correct, but for tb2 value is MyText.
                DataColumn dc = drv.Row.Table.Columns[binding.ParentBinding.Path.Path];
                if (dc != null)
                {
                    AssociatedObject.MaxLength = dc.MaxLength;
                }