Question

我有DataGrid ContextMenu，我正在试图弄清楚如何正确绑定上下文。

到目前为止，我已经阅读了上下文菜单，它位于可视树之外，因此DataContext是不同的。考虑到这一点，提供的解决方案是使用属性Tag，但我仍然无法使其工作：

<UserControl>
    <!--#region DataGrid-->

    <DataGrid ItemsSource="{Binding Model.Collection}"
              Tag="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}, Path=DataContext}">

        <!--#region Resources-->

        <DataGrid.Resources>

            <!--#region DataGridCell-->

            <Style TargetType="DataGridCell">

                <Setter Property="ContextMenu">
                    <Setter.Value>
                        <ContextMenu DataContext="{Binding PlacementTarget.Tag, RelativeSource={RelativeSource Self}}">
                            <MenuItem Header="Open Details"
                                      Command="{Binding DataContext.OpenRowDetailsCommand, RelativeSource={RelativeSource AncestorType=ContextMenu}}"
                                      CommandParameter="{Binding DataContext.SelectedIndex, RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
                        </ContextMenu>
                    </Setter.Value>
                </Setter>

            </Style>

            <!--#endregion DataGridCell-->

        </DataGrid.Resources>

        <!--#endregion Resources-->

        <!--#region DataGridColumns-->

        <DataGrid.Columns>
            <DataGridTextColumn Header="Filename"
                                Binding="{Binding FileInfo.Name}"
                                Width="Auto" />
        </DataGrid.Columns>

        <!--#endregion DataGridColumns-->

    </DataGrid>

    <!--#endregion DataGrid-->

DataContext的{{1}}工作正常，因为我有其他使用UserControl的命令。

有人看到任何错误或有任何其他方法吗？

提前致谢。

Answer 1

如果OpenRowDetailsCommand和SelectedIndex属性在父UserControl的视图模型类中定义，则此方法应该有效：

<Style TargetType="DataGridCell">
    <Setter Property="Tag" Value="{Binding RelativeSource={RelativeSource AncestorType=UserControl}}" />
    <Setter Property="ContextMenu">
        <Setter.Value>
            <ContextMenu>
                <MenuItem Header="Open Details"
                          Command="{Binding PlacementTarget.Tag.DataContext.OpenRowDetailsCommand, RelativeSource={RelativeSource AncestorType=ContextMenu}}"
                          CommandParameter="{Binding PlacementTarget.Tag.DataContext.SelectedIndex, RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
            </ContextMenu>
        </Setter.Value>
    </Setter>
</Style>

Answer 2

我喜欢使用BindingProxy（如this SO answer中所述）

public class BindingProxy : Freezable
{
    protected override Freezable CreateInstanceCore()
    {
        return new BindingProxy();
    }

    public object Data
    {
        get { return (object)GetValue(DataProperty); }
        set { SetValue(DataProperty, value); }
    }

    public static readonly DependencyProperty DataProperty =
        DependencyProperty.Register("Data", typeof(object),typeof(BindingProxy));
}

像这样使用：

<DataGrid ItemsSource="{Binding Model.Collection}">
    <DataGrid.Resources>
        <local:BindingProxy x:Key="VMProxy" Data="{Binding}" />
        <local:BindingProxy x:Key="DataGridProxy" Data="{Binding RelativeSource={RelativeSource Self}}" />
        <Style TargetType="DataGridCell">
            <Setter Property="ContextMenu">
                <Setter.Value>
                    <ContextMenu>
                        <MenuItem Header="Open Details"
                                  Command="{Binding Data.OpenRowDetailsCommand, Source={StaticResource VMProxy}}" 
                                  CommandParameter="{Binding Data.SelectedIndex, Source={StaticResource DataGridProxy}}"/>
                    </ContextMenu>
                </Setter.Value>
            </Setter>
        </Style>
    </DataGrid.Resources>

ContextMenu上的DataContext绑定

2 个答案: