DataTemplate中的EventToCommand

Question

我使用MVVM-light-Toolkit中的EventToCommand类来处理WPF-DataGrid中的AutoGeneratingColumn-Event。它在我的主数据网格中工作得很好，但是我在RowDetailsTemplate中使用了另一个DataGrid，在这里我遇到了一个问题:在生成EventToCommand-Object之前触发AutoGeneratingColumn。这个问题有解决方案吗？这是我的Xaml代码的一部分：

<DataGrid DockPanel.Dock="Top" AutoGenerateColumns="True" Name="table" VerticalAlignment="Top" ItemsSource="{Binding PartBatchList}" IsReadOnly="True">
    <i:Interaction.Triggers>
            <i:EventTrigger EventName="AutoGeneratingColumn">
                <hgc:EventToCommand Command="{Binding AutoGeneratingColumnCommand}" PassEventArgsToCommand="True"/>
            </i:EventTrigger>
        </i:Interaction.Triggers>
    <DataGrid.RowDetailsTemplate>
        <DataTemplate>
            <StackPanel Margin="30,0,30,30" Orientation="Vertical">
                <Border CornerRadius="4" Padding="5" Background="White">
                    <DataGrid ItemsSource="{Binding Workpieces}"  
                                    CanUserReorderColumns="False" CanUserResizeColumns="False" CanUserSortColumns="False"
                                    AutoGenerateColumns="True" AutoGeneratingColumn="WorkpieceListAutoGeneratingColumn">
                        <i:Interaction.Triggers>
                            <i:EventTrigger EventName="AutoGeneratingColumn">
                                <hgc:EventToCommand Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type DataGrid},AncestorLevel=2}, Path=DataContext.AutoGeneratingColumnCommand}" PassEventArgsToCommand="True"/>
                            </i:EventTrigger>
                        </i:Interaction.Triggers>
                    </DataGrid>
                </Border>
            </StackPanel>
        </DataTemplate>
    </DataGrid.RowDetailsTemplate>

</DataGrid>

调用代码隐藏文件中的事件处理程序WorkpieceListAutoGeneratingColumn，而从不调用my ViewModel中的命令。

安德烈亚斯

Answer 1

你不必在后面使用邪恶的代码;-)你可以使用附加的行为来做到这一点……

public class AutoGeneratingColumnEventToCommandBehaviour
{
    public static readonly DependencyProperty CommandProperty =
        DependencyProperty.RegisterAttached(
            "Command", 
            typeof(ICommand), 
            typeof(AutoGeneratingColumnEventToCommandBehaviour),
            new PropertyMetadata(
                null,
                CommandPropertyChanged));

    public static void SetCommand(DependencyObject o, ICommand value)
    {
        o.SetValue(CommandProperty, value);
    }

    public static ICommand GetCommand(DependencyObject o)
    {
        return o.GetValue(CommandProperty) as ICommand;
    }

    private static void CommandPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var dataGrid = d as DataGrid;
        if (dataGrid != null)
        {
            if (e.OldValue != null)
            {
                dataGrid.AutoGeneratingColumn -= OnAutoGeneratingColumn;
            }
            if (e.NewValue != null)
            {
                dataGrid.AutoGeneratingColumn += OnAutoGeneratingColumn;
            }
        }
    }

    private static void OnAutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
    {
        var dependencyObject = sender as DependencyObject;
        if (dependencyObject != null)
        {
            var command = dependencyObject.GetValue(CommandProperty) as ICommand;
            if (command != null && command.CanExecute(e))
            {
                command.Execute(e);
            }
        }
    }
}

然后在XAML中使用它，如下所示。

<DataGrid ItemsSource="{Binding MyGridSource}"
          AttachedCommand:AutoGeneratingColumnEventToCommandBehaviour.Command="{Binding CreateColumnsCommand}">
</DataGrid>