綁定到附加行為

Question

我創建了一個自定義附加行為：

public static class CustomItemsBehaviour
{
    public static readonly DependencyProperty MyTestProperty =
     DependencyProperty.RegisterAttached(
         "MyTest",
         typeof(string),
         typeof(ItemsControl),
         new UIPropertyMetadata(""));

     public static string GetMyTest(ItemsControl itemsControl)
     {
        return (string)itemsControl.GetValue(MyTestProperty);
     }

     public static void SetMyTest(ItemsControl itemsControl, string value)
     {
        itemsControl.SetValue(MyTestProperty, value);
     }
}

我正在嘗試像這樣使用它：

<ListBox
    ItemsSource="{Binding Path=Items}" 
    AttachedBehaviours:CustomItemsBehaviour.MyTest="{Binding TestValue}">

但是它失敗了：

{"A 'Binding' cannot be set on the 'SetMyTest' property of type 'ListBox'. A 'Binding' can only be set on a DependencyProperty of a DependencyObject."}

我想將視圖模型中的某些值綁定到MyTest的值。 這可能嗎？

Answer 1

問題出在您的注冊碼中。 您應該將typeof(CustomItemsBehaviour)傳遞為所有者類型：

public static readonly DependencyProperty MyTestProperty =
 DependencyProperty.RegisterAttached(
     "MyTest",
     typeof(string),
     typeof(CustomItemsBehaviour),
     new UIPropertyMetadata(""));

Answer 2

我不確定您要達到的目標，但是我認為附加財產聲明中存在一些錯誤。 嘗試這個 ：

public static class CustomItemsBehaviour
{
public static readonly DependencyProperty MyTestProperty =
 DependencyProperty.RegisterAttached(
     "MyTest",
     typeof(string),
     typeof(CustomItemsBehaviour),
     new UIPropertyMetadata(""));

 public static string GetMyTest(DependencyObject itemsControl)
 {
    return (string)itemsControl.GetValue(MyTestProperty);
 }

 public static void SetMyTest(DependencyObject itemsControl, string value)
 {
    itemsControl.SetValue(MyTestProperty, value);
 }

}

看到這里DependencyProperty.RegisterAttached