WP7：为什么 ListBox.ItemsPanel 会破坏我的 ElementName 数据绑定？

发布于 2024-10-11 00:02:30 字数 1431 浏览 0 评论 0原文

我有一个绑定到整数列表的 Windows Phone 7 ListBox。我使用的是默认的 MVVM Light 模板，因此有一个包含数据和简单的 RelayCommand 的 ViewModel 类。这是列表框：

<ListBox ItemsSource="{Binding MyData}">
    <ListBox.ItemTemplate>
        <DataTemplate>                        
            <Button Content="{Binding}">
                <i:Interaction.Triggers>
                    <i:EventTrigger EventName="Click">
                        <cmd:EventToCommand Command="{Binding ElementName=ContentGrid, Path=DataContext.TestCommand}"
                                            CommandParameter="{Binding}" />
                    </i:EventTrigger>
                </i:Interaction.Triggers>
            </Button>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

它显示按钮内整数的垂直列表。如果单击其中任何一个，则会执行以下命令代码并显示弹出窗口： new RelayCommand(i => MessageBox.Show("Test" + i));

但是，如果我只是添加以下 XAML 来更改为水平列表，则数据绑定会失败。单击该按钮时不会发生任何事情，并且不会将错误消息写入“输出”窗口。

<ListBox.ItemsPanel>
    <ItemsPanelTemplate>
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" />
    </ItemsPanelTemplate>
</ListBox.ItemsPanel>

我尝试了 EventToCommand 的一些其他类型的绑定。例如，将我的 ViewModel 指定为静态资源。它可以工作，但不如上面的示例理想。

为什么 ItemsPanel 会破坏数据绑定？

原文

I have a Windows Phone 7 ListBox that binds to a list of integers. I am using the default MVVM Light template, so there is a ViewModel class that contains data and a simple RelayCommand. Here is the ListBox:

<ListBox ItemsSource="{Binding MyData}">
    <ListBox.ItemTemplate>
        <DataTemplate>                        
            <Button Content="{Binding}">
                <i:Interaction.Triggers>
                    <i:EventTrigger EventName="Click">
                        <cmd:EventToCommand Command="{Binding ElementName=ContentGrid, Path=DataContext.TestCommand}"
                                            CommandParameter="{Binding}" />
                    </i:EventTrigger>
                </i:Interaction.Triggers>
            </Button>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

This displays a vertical list of integers inside buttons. If you click any of them, the following command code executes and shows a pop-up: new RelayCommand<int>(i => MessageBox.Show("Test" + i));

However, if I simply add the following XAML to change to a horizontal list, the databinding fails. Nothing happens when you click the button and no error messages are written to the Output window.

<ListBox.ItemsPanel>
    <ItemsPanelTemplate>
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" />
    </ItemsPanelTemplate>
</ListBox.ItemsPanel>

I have tried some other types of binding for the EventToCommand. For example, specifying my ViewModel as a static resource. It works, but is less ideal than the example above.

Why does that ItemsPanel break the databinding?

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寻找一个思念的角度 2024-10-18 00:02:30

这是 Silverlight 3 的一个已知问题。要解决此问题，请将您的 DataTemplate 包装在 UserControl 中：

    <UserControl x:Class="SilverlightApplication.MyUserControl">
        <Button Content="{Binding}">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="Click">
                    <cmd:EventToCommand Command="{Binding ElementName=ContentGrid, Path=DataContext.TestCommand}"
                                        CommandParameter="{Binding}" />
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </Button>
    </UserControl>

并使用它：

<ListBox ItemsSource="{Binding MyData}">
    <ListBox.ItemTemplate>
        <DataTemplate>                        
            <local:MyUserControl />
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

This is a known problem with Silverlight 3. To work around this, wrap your DataTemplate in a UserControl:

    <UserControl x:Class="SilverlightApplication.MyUserControl">
        <Button Content="{Binding}">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="Click">
                    <cmd:EventToCommand Command="{Binding ElementName=ContentGrid, Path=DataContext.TestCommand}"
                                        CommandParameter="{Binding}" />
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </Button>
    </UserControl>

And use it instead:

<ListBox ItemsSource="{Binding MyData}">
    <ListBox.ItemTemplate>
        <DataTemplate>                        
            <local:MyUserControl />
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

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