Question

我正在处理带有telerik控件的WPF应用程序。

我使用绑定到集合的RadListBox。当我选择每个RadListBoxItem时，BindedItem的详细视图将显示在附近的面板中。一次只能选择一个RadListBoxItem。

在下面的逻辑中，我提供了以下功能，

修改
切换到新
保存或放弃警报
保存/放弃
加载选定的

现在问题是当为Save / Discard抛出警报时，如果我单击save，则启动保存过程但在保存完成之前，加载也在另一个线程中运行。我必须检查保存是否完成并开始加载过程。

// XAML代码：

<telerik:RadListBox x:Name="lstMarketSeries" ItemsSource="{Binding SCollection, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True}" SelectedItem="{Binding SelectedMSeries, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" telerik:StyleManager.Theme="Windows8"> 
<i:Interaction.Triggers>
   <i:EventTrigger EventName="SelectionChanged">
     <i:InvokeCommandAction Command="{Binding LoadSelected}"/>
   </i:EventTrigger>
</i:Interaction.Triggers>
</telerik:RadListBox>

//视图模型：

public ICommand LoadSelected { get { return new RelayCommand(LoadSelectedSDetails); } }

/// <summary>
/// Load selected series
/// </summary>
private async void LoadSelectedSDetails()
{
   if (SCollection != null)
   {
       if (!IsChanged())
       {
           bw = new BackgroundWorker();
           bw.RunWorkerAsync();

           bw.DoWork += (s, e) =>
           {
                //Loading functionality here( Have to check if the save is complete)
           };

           bw.RunWorkerCompleted += (s, e) =>
           {
                IsBusy = false;
           };
       }
       else
       { 
           await PutTaskDelay();  // This delay is to wait for save to complete
           LoadSelectedSDetails();
       }

/// <summary>
/// Check if collection is changed
/// </summary>
private bool IsChanged()
{
    bool IsChanged = false;
    if (SCollection != null)
       IsChanged = SCollection.Where(x => x.IsChanged || x.IsNew).Count() > 0;

    if (IsChanged)
    {
       if (ShowMessages.SaveOrDiscardBox())
       {
          SaveAllDetails(); // Saving runs in a separate thread.
       }
       else
       {
          //Discard functionality goes here
       }
    }

    return IsChanged;
}

请帮助解决这个问题。

Answer 1

如果您想在Task执行后执行某些操作，可以使用ContinueWith：

       var saveTask = new Task<ReturnedObject>(() =>  //if you don't need values in order to update the UI you can use Task not Task<T>
                    {
                      //do your save action and return something if you want 
                    });

                    //start thread
                    saveTask.Start();

                    saveTask.ContinueWith(previousTask =>
                    {//after the first thread is completed, this point will be hit

                        //loading action here

                        //UI region if needed
                            Application.Current.Dispatcher.BeginInvoke((ThreadStart)delegate
                            {
                              //update UI
                            }, DispatcherPriority.Render);               

                    }, TaskScheduler

    .FromCurrentSynchronizationContext());

并发多线程C＃

1 个答案: