WinUI3数据模板对象中Interaction.Behaviors失效问题求助

在Uno Platform（WinUI/.NET6）项目中，为TabViewItem、TreeViewItem和ListViewItem配置了多数据模板，通过ItemInvoked（TreeView）、DoubleTapped（ListView）、CloseRequested（TabView）等事件，借助Interaction.Behaviors绑定命令触发操作。但出现异常：这些命令在调用几次后就会失效，但相同的命令通过Button的Command绑定却能持续正常工作。

复现示例（TabView关闭操作） #

通常前3-5个标签页可正常响应CloseRequested事件绑定的命令，之后失效：

<DataTemplate x:Key="HtmlFileTemplate" x:DataType="local:FileContentViewModel">
    <TabViewItem Header="{x:Bind Info.Name}">
        <StackPanel Orientation="Vertical">
            <TextBlock Text="{x:Bind Content}" />
            <!-- 该按钮绑定的命令始终正常工作 -->
            <Button Command="{x:Bind CloseCommand}">Invoke FileContentViewModel.CloseCommand</Button>
        </StackPanel>
        <!-- 该行为绑定的命令在几次调用后失效 -->
        <i:Interaction.Behaviors>
            <ic:EventTriggerBehavior EventName="CloseRequested">
                <ic:InvokeCommandAction Command="{x:Bind CloseCommand}" />
            </ic:EventTriggerBehavior>
        </i:Interaction.Behaviors>
    </TabViewItem>
</DataTemplate>

<local:TabsTemplateSelector x:Key="TabsTemplateSelector" HtmlFileTemplate="{StaticResource HtmlFileTemplate}" ... />
...

<TabView TabItemsSource="{x:Bind ViewModel.Tabs}" TabItemTemplateSelector="{StaticResource TabsTemplateSelector}">
</TabView>

使用环境配置 #

• 项目初始化：dotnet new unoapp -o UnoWinUI3AppName
• 依赖包版本：
  • CommunityToolkit.Mvvm 7.1.2
  • Microsoft.WindowsAppSDK 1.1.3
  • Microsoft.Windows.SDK.BuildTools 10.0.22621.1
  • Uno.Microsoft.Xaml.Behaviors.Interactivity.WinUI 2.3.0
  • Uno.Microsoft.Xaml.Behaviors.WinUI.Managed 2.3.0

临时解决方案：自定义附加属性绑定行为 #

通过自定义附加属性的方式绑定行为，可规避命令失效问题：

C# 附加属性实现

public static class InteractionEx
{
    public static readonly DependencyProperty AttachBehaviorsProperty = DependencyProperty.RegisterAttached
    (
        "AttachBehaviors",
        typeof(object),
        typeof(FrameworkElement),
        new PropertyMetadata(false, AttachBehaviorsChanged)
    );

    public static object GetAttachBehaviors(DependencyObject o) => o.GetValue(AttachBehaviorsProperty);

    public static void SetAttachBehaviors(DependencyObject o, object value) => o.SetValue(AttachBehaviorsProperty, value);


    private static void AttachBehaviorsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var behaviors = e.NewValue switch
        {
            Behavior single => new BehaviorCollection { single },
            BehaviorCollection multiple => multiple,
            _ => null,
        };

        Interaction.SetBehaviors(d, behaviors);
    }
}

XAML 使用示例

<ListView ItemsSource="{x:Bind Items}" ItemTemplateSelector="{StaticResource ListItemTemplateSelector}" SelectedItem="{x:Bind SelectedItem, Mode=TwoWay}">
    <local:InteractionEx.AttachBehaviors>
        <interactivity:BehaviorCollection>
            <core:EventTriggerBehavior EventName="DoubleTapped">
                <core:InvokeCommandAction Command="{x:Bind OpenCommand}" />
                <core:CallMethodAction MethodName="Open" TargetObject="{x:Bind}" />
            </core:EventTriggerBehavior>
        </interactivity:BehaviorCollection>
    </local:InteractionEx.AttachBehaviors>
</ListView>

内容的提问来源于stack exchange，提问作者sharpener