WP7：为什么一个ListBox.ItemsPanel打破我的ElementName数据绑定？ [英] WP7: Why does a ListBox.ItemsPanel break my ElementName data binding?

问题描述

我有一个Windows Phone 7的的ListBox 结合整数列表。我使用的是默认的MVVM光模板，所以有一个视图模型类包含数据和一个简单的 RelayCommand 。这里是列表框：

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>

这里面显示的按钮整数垂直列表。如果你点击其中任何一个，以下命令代码执行，并显示一个弹出：新RelayCommand< INT>（I => MessageBox.Show（测试+ I））;

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));

不过，如果我只是添加下面的XAML更改为水平列表，数据绑定失败。当你单击该按钮并没有错误消息被写入到输出窗口什么也没有发生。

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>

我曾尝试为 EventToCommand 。例如，指定我视图模型作为静态的资源。它的工作原理，但比上面的例子不太理想。

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.

为什么说 ItemsPanel 打破绑定？

推荐答案

这是一个已知的问题与 Silverlight 3的。要解决这个问题，换你的的DataTemplate 在用户控件：

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>

和使用它来代替：

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

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