c# – 无法将Observable Collection绑定到UserControl上的附加属性

2023年1月16日 164次阅读

我想将自定义类型(BoundItem)的ObservableCollection绑定到视图.

我这样使用它：

<v:MyUserControlBase x:Class="My.Views.MyView"
         (...)
         h:FrameworkElementDropBehavior.MyItems="{Binding Attachments}">

附件在ViewModel中定义为：

public ObservableCollection<BoundItem> Attachments 
{ 
   get { return _Attachments; } 
   set { _Attachments = value; } 
}

我的视图是一个实际的DependencyObject,因为当我在视图后面的代码中执行以下代码时：

MessageBox.Show((this as DependencyObject).ToString());

它显示“真实”.

我这样定义了我的Dependency Property：

    public static readonly DependencyProperty MyItemsProperty = DependencyProperty.RegisterAttached("MyItems", typeof(ObservableCollection<BoundItem>), typeof(MyView), new FrameworkPropertyMetadata(null));
    public static string GetMyItems(DependencyObject element)
    {
        if (element == null) throw new ArgumentNullException("MyItems");
        return (ObservableCollection<BoundItem>)element.GetValue(MyItemsProperty);
    }
    public static void SetMyItems(DependencyObject element, ObservableCollection<BoundItem> value)
    {
        if (element == null) throw new ArgumentNullException("MyItems");
        element.SetValue(MyItemsProperty, value);
    }

发生的错误是：

A ‘Binding’ cannot be set on the ‘SetMyItems’ property of type ‘MyView’. A ‘Binding’ can only be set on a DependencyProperty of a DependencyObject.

谢谢你的帮助:) .x

最佳答案 问题在于您的财产注册.而不是所有者类型MyView它应该是FrameworkElementDropBehavior i,即您定义属性的类.

public static readonly DependencyProperty MyItemsProperty =
     DependencyProperty.RegisterAttached("MyItems", 
                                        typeof(ObservableCollection<BoundItem>), 
                                        typeof(FrameworkElementDropBehavior), 
                                        new FrameworkPropertyMetadata(null));
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