绑定到 DataTemplate 中的父 DataContext

发布于 2024-12-07 01:03:10 字数 1297 浏览 0 评论 0原文

我正在尝试将 MenuItem 的命令绑定到 UserControl.DataContext 中包含的命令。我发现了几个类似的问题，但根据他们的解决方案对我来说失败了：

<UserControl ...>
<UserControl.Resources>
    <DataTemplate x:Key="TileItemStye">
        <Grid Width="100" Height="100">
            <Grid.ContextMenu>
                <ContextMenu>
                    <MenuItem Header="Remove" 
                              Command="{Binding DataContext.RemoveItem, 
                              RelativeSource={RelativeSource FindAncestor,
                                             AncestorType=UserControl}}">
                    </MenuItem>
                </ContextMenu>
            </Grid.ContextMenu>
        </Grid>
    </DataTemplate>
</UserControl.Resources>
<Grid>
    <ListView ItemsSource="{Binding Path=Files}" 
              ItemTemplate="{DynamicResource TileItemStye}"  >
    <ListView.ItemsPanel>
        <ItemsPanelTemplate>
            <WrapPanel />
        </ItemsPanelTemplate>
    </ListView.ItemsPanel>
</ListView>
</Grid>

UserControl 的 DataContext 是带有 ICommandRemoveItem 和 ObservableCollection 文件的 ViewModel。

原文

I'm trying to bind MenuItem's Command to command contained in UserControl.DataContext. I've found couple of similar question, but solution according to them is failing to me:

<UserControl ...>
<UserControl.Resources>
    <DataTemplate x:Key="TileItemStye">
        <Grid Width="100" Height="100">
            <Grid.ContextMenu>
                <ContextMenu>
                    <MenuItem Header="Remove" 
                              Command="{Binding DataContext.RemoveItem, 
                              RelativeSource={RelativeSource FindAncestor,
                                             AncestorType=UserControl}}">
                    </MenuItem>
                </ContextMenu>
            </Grid.ContextMenu>
        </Grid>
    </DataTemplate>
</UserControl.Resources>
<Grid>
    <ListView ItemsSource="{Binding Path=Files}" 
              ItemTemplate="{DynamicResource TileItemStye}"  >
    <ListView.ItemsPanel>
        <ItemsPanelTemplate>
            <WrapPanel />
        </ItemsPanelTemplate>
    </ListView.ItemsPanel>
</ListView>
</Grid>

UserControl's DataContext is ViewModel with ICommand RemoveItem and ObservableCollection<FileViewModel> Files.

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青朷 2024-12-14 01:03:10

如果您使用.NET 4，确实有一个更优雅的解决方案：

<UserControl Name="uc" ...>
<!-- ... -->
    <MenuItem Header="Remove"
              Command="{Binding DataContext.RemoveItem,
                                Source={x:Reference uc}}"/>

（这要求模板保留在资源中，否则会出现循环依赖错误）

If you are on .NET 4 there indeed is a more elegant solution:

<UserControl Name="uc" ...>
<!-- ... -->
    <MenuItem Header="Remove"
              Command="{Binding DataContext.RemoveItem,
                                Source={x:Reference uc}}"/>

(This requires that the template stays in the Resources, otherwise there will be a cyclical dependency error)

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末蓝 2024-12-14 01:03:10

菜单与控件不在同一视觉树中绘制，这就是为什么relativesource绑定不起作用的原因

您需要绑定到ContextMenu的PlacementTarget才能访问主菜单视觉树

<MenuItem Header="Remove" 
          Command="{Binding PlacementTarget.DataContext.RemoveItem, 
              RelativeSource={RelativeSource FindAncestor, 
              AncestorType={x:Type ContextMenu}}}" />

Menus are not drawn in the same Visual Tree as your Controls, which is why the RelativeSource binding does not work

You need to bind to the PlacementTarget of your ContextMenu to access the main Visual Tree

<MenuItem Header="Remove" 
          Command="{Binding PlacementTarget.DataContext.RemoveItem, 
              RelativeSource={RelativeSource FindAncestor, 
              AncestorType={x:Type ContextMenu}}}" />

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