Question

在WPF（C＃）应用程序中，我的目标是从子视图中执行删除命令。 Delete命令将从上级集合中删除对象本身。这是孩子的数据模板（来自.xaml文件）

<DataTemplate DataType="{x:Type dataModel:AppLeg}">
  <Menu Grid.Column="2">
   <MenuItem Header="Delete Leg" Command="{Binding DeleteLegCommand}" 
     CommandParameter="{Binding}"/> 
  </Menu>
 </DataTemplate>

 <DataTemplate DataType="{x:Type dataModel:DestinationSchedule}">        
        <ItemsControl dd:DragDrop.IsDragSource="True"
                      dd:DragDrop.IsDropTarget="True"
                      dd:DragDrop.DropHandler="{Binding}"
                      Focusable="False"
                      ItemsSource="{Binding AppLegs}"
                      SnapsToDevicePixels="True"
                       FontWeight="SemiBold"
                      UseLayoutRounding="True">               
        </ItemsControl>            
    </DataTemplate>

在DataModel中，正在执行Command_DeleteTripLeg方法，这意味着还调用了Event EventDeleteLeg。

   public class AppLeg
    {
   public event Action<AppLeg> EventDeleteLeg;
   public RelayCommand<object> DeleteTripLegCommand => new 
        RelayCommand<object>(Command_DeleteLeg, true);

    private void Command_DeleteTripLeg(object leg )
    {
        EventDeleteLeg?.Invoke((AppLeg)Leg);
    }

现在，在父类（AppLeg类的Collection类）中，我有Appleg类的collection对象。

public class DestinationSchedule : ViewModelBase
{
    #region Fields

    private ObservableCollection<AppLeg> _appLegs;

    private void deleteAppLegFromCollection( AppLeg appLeg)
    {
       _appLegs.Remove( appLeg )
    }
}

所以我的目标是将父DestinationSchedule模型类的deleteAppLegFromCollection（）方法订阅到EventDeleteLeg事件，以便在执行“ DeleteLegCommand”命令时，可以从集合_tripLegs中删除该AppLeg对象。

AppDestination.cs类

public class AppDestination : ViewModelBase
  {
    private ObservableCollection<DestinationSchedule> _destinationSchedule;

    public ObservableCollection<DestinationSchedule> DestinationSchedule
    {
        get => _destinationSchedule;
        set => Set(ref _destinationSchedule, value);
    }
}

ScheduleDestinationsView.xaml代码

<d:UserControl.DataContext>
    <viewModel:ScheduleDestinationsViewModel/>
</d:UserControl.DataContext>
<UserControl.Resources>
    <ResourceDictionary>
        <ResourceDictionary.MergedDictionaries>                
            <ResourceDictionary 
            Source="pack://application:,,,/SharedResources;
                                component/DataTemplates.xaml"/>
        </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
</UserControl.Resources>

  <Grid SnapsToDevicePixels="True" UseLayoutRounding="True">
    <ListBox VerticalAlignment="Stretch"
                  VerticalContentAlignment="Stretch"
                  Focusable="False"
                  ItemsSource="{Binding AppDestinations}">
        <ItemsControl.Template>
            <ControlTemplate>
                <ItemsPresenter/>
            </ControlTemplate>
        </ItemsControl.Template>
        </ListBox>
         </Grid>

和ScheduleDestinationsViewModel.cs类

public class ScheduleDestinationsViewModel : ViewModelBase
{       
    private ObservableCollection<AppDestination> _appDestinations;
    public ObservableCollection<AppDestination> AppDestinations
    {
        get => _appDestinations;
        set => Set(ref _appDestinations, value);
    }

    public ScheduleDestinationsViewModel()
    {
        AppDestinations = new ObservableCollection<AppDestination>();
    }
}

父类如何订阅子类活动？请指教。另一种方法也很不错。谢谢。

Answer 1

将delete命令移动到定义了DestinationSchedule源集合的父类（AppLegs）上，并调用该命令的命令。

您可以通过指定RelativeSource绑定到父元素的命令：

<Menu Grid.Column="2">
    <MenuItem Header="Delete Leg" Command="{Binding DataContext.DeleteLegCommand, RelativeSource={RelativeSource AncestorType=ItemsControl}}" 
              CommandParameter="{Binding}"/>
</Menu>

父类方法如何订阅子类Event？

1 个答案: