Question

我在使用上下文菜单执行复制操作时随机获取异常 “无法将'MS.Internal.NamedObject'类型的对象强制转换为类型TreeItemViewModel”

以下是我的上下文菜单的代码

<ContextMenu x:Key="MyContextMenu" >
        <ContextMenu.Resources>
            <obj:BindingProxy x:Key="vmProxy" Data="{Binding RelativeSource={RelativeSource AncestorType=ContextMenu}, Path=PlacementTarget, Converter={StaticResource FindNamedElementFromSourceTreeConverter}, ConverterParameter=MyTreeView}"/>
            <obj:BindingProxy x:Key="modelProxy" Data="{Binding RelativeSource={RelativeSource AncestorType=ContextMenu}, Path=PlacementTarget.DataContext}"/>
        </ContextMenu.Resources>

 <MenuItem Header="{core:Localization Key=Copy}" 
                  CommandParameter="{Binding Source={StaticResource modelProxy}, Path=Data}"
                  Command="{Binding Source={StaticResource vmProxy}, Path=Data.DataContext.CopyCommand}">
        </MenuItem>
 </ContextMenu>

此上下文菜单用于我的树视图项目样式，如下所示

<Style x:Key="MyTreeViewItemStyle" TargetType="TreeViewItem">

        <Style.Triggers>
            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=DataContext, Converter={StaticResource TypeOfConverter}}" Value="{x:Type models:MyModel1}">                
                <Setter Property="ContextMenu" Value="{StaticResource MyContextMenu}"/>
            </DataTrigger>
        </Style.Triggers>
    </Style>

此样式将添加到Treeview中，如下所示

<TreeView x:Name="MyTreeView"
                          DockPanel.Dock="Top"
                          Padding="0"
                          ItemsSource="{Binding MyTreeItems}"
                          BorderThickness="0"                         
                          ItemContainerStyle="{StaticResource MyTreeViewItemStyle}"/>

这是我的转换器

 public class FindNamedElementFromSourceTreeConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            string name = parameter as string;
            if (string.IsNullOrEmpty(name)) return null;


            DependencyObject dp = value as DependencyObject;
            if (dp == null) return null;

            DependencyObject root = DependencyObjectHelper.FindRootElement(dp);
            if (root == null) return null;

            DependencyObject result = DependencyObjectHelper.FindChild(root, name);
            return result;
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

当通过右键单击treeviewItem上下文菜单项执行excecute copy命令时，会出现“无法转换类型对象”异常。 UI中的另一个按钮使用了相同的复制命令，该按钮工作正常，没有任何问题。请让我知道如何解决这个问题..

无法将类型为“MS.Internal.NamedObject”的对象强制转换为类型TreeItemViewModel

0 个答案: