如何为WPF DataGrid每行添加带参数的MouseDoubleClick命令触发？

问题 #

我在XAML中有一个DataGrid，想要给每个DataGridRow添加MouseDoubleClick事件，调用带参数的命令。但遇到两个限制：

• 无法用EventSetter绑定命令（因为需要传递参数）；
• 不能用代码后置：一是用了ViewModel定位器，强转DataContext不够优雅；二是目标方法是异步方法，而事件Handler要求返回void而非Task。

原XAML代码 #

<DataGrid
     AutoGenerateColumns="False"
     Grid.Row="2"
     IsReadOnly="True"
     ItemsSource="{Binding Entities, Converter={x:Static convertors:FileEntityEnumerableToFileDataGridEntityEnumerableConvertor.Instance}}"
     Name="ViewerDataGrid"
     SelectedItem="{Binding SelectedItem}"
     Visibility="{Binding IsDataGridVisible, Converter={x:Static materialDesign:BooleanToVisibilityConverter.HiddenInstance}}">
     <DataGrid.Resources>
          <Style BasedOn="{StaticResource MaterialDesignDataGridColumnHeader}" TargetType="DataGridColumnHeader">
              <Setter Property="Background" Value="{Binding ElementName=CloseButton, Path=Background}" />
          </Style>

          <Style BasedOn="{StaticResource MaterialDesignDataGridCell}" TargetType="DataGridCell">
              <Style.Triggers>
                  <Trigger Property="IsSelected" Value="True">
                      <Setter Property="BorderBrush" Value="Transparent" />
                  </Trigger>
              </Style.Triggers>
          </Style>
     </DataGrid.Resources>
     <DataGrid.Columns>
         <DataGridTextColumn Binding="{Binding Name}" Header="Name" />
         <DataGridTextColumn Binding="{Binding Size}" Header="Size" />
         <DataGridTextColumn Binding="{Binding LastChanging}" Header="Last changing" />
         <DataGridTextColumn Binding="{Binding CreatedAt}" Header="Created at" />
     </DataGrid.Columns>
     <DataGrid.RowStyle>
         <Style BasedOn="{StaticResource {x:Type DataGridRow}}" TargetType="{x:Type DataGridRow}">
             <Setter Property="i:Interaction.Triggers">
                 <Setter.Value>
                     <i:Interaction.Triggers>
                         <i:EventTrigger EventName="MouseDoubleClick">
                             <i:InvokeCommandAction Command="{Binding DataContext.ResetDirectoryContentCommand, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" CommandParameter="{Binding}" />
                         </i:EventTrigger>
                     </i:Interaction.Triggers>
                 </Setter.Value>
             </Setter>
         </Style>
     </DataGrid.RowStyle>
</DataGrid>

尝试过的无效方式 #

<DataGrid.RowStyle>
     <Style BasedOn="{StaticResource {x:Type DataGridRow}}" TargetType="{x:Type DataGridRow}">
         <EventSetter Event="MouseDoubleClick" Handler="{Binding DataContext.ResetDirectoryContentCommand, RelativeSource={RelativeSource AncestorType=DataGrid}}" />
     </Style>
</DataGrid.RowStyle>

解决方案 #

方案1：使用Microsoft.Xaml.Behaviors（Blend交互行为） #

你原XAML中的写法方向是对的，只需补充异步命令的实现即可：

1. 引入NuGet包：安装Microsoft.Xaml.Behaviors.Wpf（WPF项目），确保XAML头部已声明命名空间：

   xmlns:i="http://schemas.microsoft.com/xaml/behaviors"
   

2. 实现异步命令：封装支持异步逻辑的ICommand，避免UI阻塞并处理重复点击：

   public class AsyncRelayCommand<T> : ICommand
   {
       private readonly Func<T, Task> _execute;
       private readonly Predicate<T> _canExecute;
       private bool _isExecuting;
   
       public event EventHandler CanExecuteChanged;
   
       public AsyncRelayCommand(Func<T, Task> execute, Predicate<T> canExecute = null)
       {
           _execute = execute ?? throw new ArgumentNullException(nameof(execute));
           _canExecute = canExecute;
       }
   
       public bool CanExecute(object parameter)
       {
           return !_isExecuting && (_canExecute?.Invoke((T)parameter) ?? true);
       }
   
       public async void Execute(object parameter)
       {
           if (!CanExecute(parameter)) return;
           _isExecuting = true;
           try
           {
               await _execute((T)parameter);
           }
           finally
           {
               _isExecuting = false;
               RaiseCanExecuteChanged();
           }
       }
   
       public void RaiseCanExecuteChanged()
       {
           CanExecuteChanged?.Invoke(this, EventArgs.Empty);
       }
   }
   

3. ViewModel中定义命令：

   public AsyncRelayCommand<YourEntityType> ResetDirectoryContentCommand { get; }
   
   public YourViewModel()
   {
       ResetDirectoryContentCommand = new AsyncRelayCommand<YourEntityType>(ExecuteResetDirectoryContent);
   }
   
   private async Task ExecuteResetDirectoryContent(YourEntityType entity)
   {
       // 你的异步业务逻辑
   }
   

4. 保留原XAML的RowStyle：你的写法已经正确绑定了命令和当前行的实体参数，只要命令是异步实现即可正常工作。

方案2：自定义附加属性（无额外依赖） #

如果不想引入第三方包，可以自己写附加属性处理事件绑定：

1. 实现附加属性类：

   public static class DataGridRowExtensions
   {
       public static readonly DependencyProperty DoubleClickCommandProperty =
           DependencyProperty.RegisterAttached(
               "DoubleClickCommand",
               typeof(ICommand),
               typeof(DataGridRowExtensions),
               new PropertyMetadata(null, OnDoubleClickCommandChanged));
   
       public static ICommand GetDoubleClickCommand(DependencyObject obj)
       {
           return (ICommand)obj.GetValue(DoubleClickCommandProperty);
       }
   
       public static void SetDoubleClickCommand(DependencyObject obj, ICommand value)
       {
           obj.SetValue(DoubleClickCommandProperty, value);
       }
   
       private static void OnDoubleClickCommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
       {
           if (d is DataGridRow row)
           {
               row.MouseDoubleClick -= Row_MouseDoubleClick;
               if (e.NewValue is ICommand command)
               {
                   row.MouseDoubleClick += Row_MouseDoubleClick;
               }
           }
       }
   
       private static async void Row_MouseDoubleClick(object sender, MouseButtonEventArgs e)
       {
           if (sender is DataGridRow row && GetDoubleClickCommand(row) is AsyncRelayCommand<object> asyncCommand)
           {
               await ((Func<object, Task>)asyncCommand.Execute).Invoke(row.DataContext);
           }
           else if (sender is DataGridRow row && GetDoubleClickCommand(row) is ICommand syncCommand)
           {
               syncCommand.Execute(row.DataContext);
           }
       }
   }
   

2. XAML中使用附加属性：
   先引入自定义类的命名空间（假设命名空间为YourNamespace）：

   xmlns:local="clr-namespace:YourNamespace"
   

   再修改RowStyle：

   <DataGrid.RowStyle>
       <Style BasedOn="{StaticResource {x:Type DataGridRow}}" TargetType="{x:Type DataGridRow}">
           <Setter Property="local:DataGridRowExtensions.DoubleClickCommand" 
                   Value="{Binding DataContext.ResetDirectoryContentCommand, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" />
       </Style>
   </DataGrid.RowStyle>
   

内容的提问来源于stack exchange，提问作者TheMakarik