uwp GridView Drop EventTriggerBehavior 签名

Question

我正在开发具有多个 ComboBox 和 GridView 的拖放 Xaml Uwp 应用程序。我在后面的 xaml 代码中对它进行了一些试验，直到我认为我知道我在使用该应用程序时要去哪里。然后我开始将我的逻辑转移到 ViewModel、PlayPageViewModel 中，我正在使用 MvvM Light 和 Template 10。我有许多使用交互的事件。当我将 Drop 移到我得到 Cannot find method named GvNewPlayList_OnDrop on object of type TheLolFx.UWP.T10.ViewModels.PlayPageViewModel that matches the expected signature.

的视图模型时，我已经在 codeBehind 中工作了 Drop

例外

        Exception   {System.ArgumentException: Cannot find method named    GvNewPlayList_OnDrop on object of type TheLolFx.UWP.T10.ViewModels.PlayPageViewModel that matches the expected signature.
       at Microsoft.Xaml.Interactions.Core.CallMethodAction.Execute(Object sender, Object parameter)
       at Microsoft.Xaml.Interactivity.Interaction.ExecuteActions(Object sender, ActionCollection actions, Object parameter)
       at Microsoft.Xaml.Interactions.Core.EventTriggerBehavior.OnEvent(Object sender, Object eventArgs)}   System.Exception {System.ArgumentException}

留言

Message "System.ArgumentException: Cannot find method named GvNewPlayList_OnDrop on object of type TheLolFx.UWP.T10.ViewModels.PlayPageViewModel that matches the expected signature.\r\n  at Microsoft.Xaml.Interactions.Core.CallMethodAction.Execute(Object sender, Object parameter)\r\n at Microsoft.Xaml.Interactivity.Interaction.ExecuteActions(Object sender, ActionCollection actions, Object parameter)\r\n  at Microsoft.Xaml.Interactions.Core.EventTriggerBehavior.OnEvent(Object sender, Object eventArgs)"  string

我使用了在后面的代码中生成的签名。 ContainerContentChanging在 ViewModel 中被触发正如你所看到的，我也尝试过使用对象。

什么是正确的签名？

XAML

<GridView x:Name="GvNewPlayList"
                      RelativePanel.Below="CbPlayListEditor"
                      Visibility="{Binding LbNewPlayListVisibility}"
                      Background="BurlyWood"
                      Padding="5"
                      Header="New Play List"
                      ItemsSource="{Binding NewLocalSoundsPlayListsSelectedItem.LocalSfxV2s}"

                      CanDragItems="True"
                      AllowDrop="True"
                      CanReorderItems="True"
                      IsItemClickEnabled="True"
                      DragItemsStarting="LbNewPlayList_OnDragItemsStarting"

                      DragOver="LbNewPlayList_OnDragOver">                   
                <interactivity:Interaction.Behaviors>
                    <core:EventTriggerBehavior EventName="Drop">
                        <core:CallMethodAction MethodName="GvNewPlayList_OnDrop"
                                               TargetObject="{Binding Mode=OneWay}" />
                    </core:EventTriggerBehavior>

                    <core:EventTriggerBehavior EventName="ContainerContentChanging">
                        <core:CallMethodAction MethodName="GvLocalSoundsPlayListEditorContainerContentChangingAsync"
                                               TargetObject="{Binding Mode=OneWay}" />
                    </core:EventTriggerBehavior>
                </interactivity:Interaction.Behaviors>

                <GridView.ItemTemplate>
                    <DataTemplate>
[...]

PlayPageViewModel

XAML 尝试在 vm 中定位此方法时引发异常。

    // private async void GvNewPlayList_OnDrop(object sender, object e)
    // private async void GvNewPlayList_OnDrop()

    private async void GvNewPlayList_OnDrop(object sender, DragEventArgs e)
    {
        e.AcceptedOperation = DataPackageOperation.Copy;
        Logger.Log(this, "yup");
        [...]
    }

这是从ContainerContentChanging 事件触发的。

    public async void GvLocalSoundsPlayListEditorContainerContentChangingAsync()
    {
        Logger.Log(this, $"GvLocalSoundsPlayListEditorContainerContentChangingAsync: {SelectedPlayList?.PlayListName}");
        //_settings.CurrentPlayList = SelectedPlayList;
        //LocalSounds = await _theLolFxV2DataServices.GetPlayListAsync(SelectedPlayList);
        //NewLocalSoundsPlayListItems = await _theLolFxV2DataServices.GetPlayListAsync(CbPlayListEditorSelectedItem);
    }

Answer 1

当使用CallMethodAction 调用方法时，方法的签名应该是这样的：public void DoSomthing()。异常原因如下：

1. GvNewPlayList_OnDrop标记为private，需要标记为public；

2. 不能包含任何参数。

所以只需像第二种方法那样修改它的签名：public async void GvLocalSoundsPlayListEditorContainerContentChangingAsync()