WPF命令绑定ItemsControl内的ContextMenu项 [英] WPF Command Binding of ContextMenu Item inside ItemsControl

问题描述

我的应用程序由一个MainWindow和一个ContentControl组成，我根据所选菜单更改ViewModel.

My Application consists of a MainWindow with a ContentControl and I change the ViewModel depending on the selected menu.

我显示为内容的UserControl之一包含以下WrapPanel:

One of the UserControls I display as content contains the following WrapPanel:

<UserControl ...>
    <Grid>
        <WrapPanel>
            <ItemsControl ItemsSource="{Binding Connections}">
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <Button Command="{Binding DataContext.ConnectionSelectCommand, RelativeSource={RelativeSource AncestorType=ItemsControl}}"
                                CommandParameter="{Binding}"
                                FocusManager.FocusedElement="{Binding ElementName=InstanceName}"
                                Style="{DynamicResource DashboardButton}">
                            <TextBlock TextWrapping="Wrap" HorizontalAlignment="Center" Text="{Binding Name}" />
                            <Button.ContextMenu>
                                <ContextMenu>
                                    <MenuItem Header="Delete"
                                              Command="{Binding ConnectionRemoveCommand}"
                                              CommandParameter="{Binding}" />
                                </ContextMenu>
                            </Button.ContextMenu>
                        </Button>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
                <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate>
                        <WrapPanel Orientation="Horizontal" />
                    </ItemsPanelTemplate>
                </ItemsControl.ItemsPanel>
            </ItemsControl>
        </WrapPanel>
    </Grid>
</UserControl>

ContextMenu上的Command无效，因为它尝试调用Connection对象上的ConnectionRemoveCommand而不是ConnectionViewModel(即UserControl的DataContext).

The Command on the ContextMenu doesn't work because it tries to call ConnectionRemoveCommand on the Connection object instead of the ConnectionViewModel which is the DataContext of the UserControl.

如何如何将Command绑定到ConnectionViewModel，并且CommandParameter是Connection对象?

How do I bind the Command to the ConnectionViewModel with the CommandParameter being the Connection object?

推荐答案

如果将Button的Tag属性绑定到ItemsControl的DataContext，则可以使用<ContextMenu的c18>:

If you bind the Tag property of the Button to the DataContext of the ItemsControl, you could then bind to it using the PlacementTarget of the ContextMenu:

<Button Command="{Binding DataContext.ConnectionSelectCommand, RelativeSource={RelativeSource AncestorType=ItemsControl}}"
        CommandParameter="{Binding}"
        FocusManager.FocusedElement="{Binding ElementName=InstanceName}"
        Style="{DynamicResource DashboardButton}"
        Tag="{Binding DataContext, RelativeSource={RelativeSource AncestorType=ItemsControl}}">
    <TextBlock TextWrapping="Wrap" HorizontalAlignment="Center" Text="{Binding Name}" />
    <Button.ContextMenu>
        <ContextMenu>
            <MenuItem Header="Delete"
                    Command="{Binding PlacementTarget.Tag.ConnectionRemoveCommand, RelativeSource={RelativeSource AncestorType=ContextMenu}}"
                    CommandParameter="{Binding}" />
        </ContextMenu>
    </Button.ContextMenu>
</Button>

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