WPF 异步任务错误未触发

Question

Maybe I am completely lost here, but I am having the hardest time figuring out what is causing my tasks to exit prematurely and any attempts at error handling has failed so far. Issue is I am stepping through hundreds of directories in a file system so step debugging to find where I am failing is impossible, plus I need to be handling errors anyway. Here is what I have so far.

Button code triggered by WPF button.

private void BtnCopy_Click(object sender, RoutedEventArgs e)
{
Dispatcher.Invoke(() => { BtnBrowse.IsEnabled = false; BtnCopy.IsEnabled = false; });

var task = Task.Run(() =>
{
  try
  {
    _ = RunCopy();
  }
  catch (Exception ex)
  {
    MessageBox.Show(ex.Message, "Error", MessageBoxButton.OK, MessageBoxImage.Error);
  }
});
}
task.ContinueWith((t) => { Dispatcher.Invoke(() => { BtnBrowse.IsEnabled = true; BtnCopy.IsEnabled = true; }); });

This message box never shows. In my RunCopy code I am cycling through the folders in a directory.

private async Task RunCopy()
{
foreach (var folder in firstDirInfo.GetDirectories())
{
  if (folder.Name.Contains(customerNumber))
  {
    await CopyTask(firstDirInfo + @"\" + folder, customerNumber);
  }
}
}

CopyTask is the event that is eventually erroring out.

private async Task CopyTask(string directory, string customerNumber)
{
var dirInfo = new DirectoryInfo(directory);

            //Create root folder
            var createFolder = copyToDir + @"\" + dirInfo.Name;
            if (!Directory.Exists(createFolder))
                Directory.CreateDirectory(createFolder);

            foreach (var folder in dirInfo.GetDirectories())
            {
                var sourceFolder = directory + @"\" + folder.Name; 
                var targetFolder = createFolder + @"\" + folder.Name;

                //Create target path if it doesn't exist
                if (!Directory.Exists(targetFolder))
                    Directory.CreateDirectory(targetFolder);

                //Now Create all of the directories
                foreach (var dirPath in Directory.GetDirectories(sourceFolder, "*", SearchOption.AllDirectories))
                {
                    if (!Directory.Exists(dirPath))
                        Directory.CreateDirectory(dirPath);
                }

                //Gather copy information
                foreach (var newPath in Directory.GetFiles(sourceFolder, "*.*", SearchOption.AllDirectories))
                {
                    masterDic.Add(newPath, newPath.Replace(sourceFolder, targetFolder));
                }
            }
}

The purpose if this is to eventually run an async file copy, I am just collecting the file information and creating directories first so I can handle the progress bar later. It errors out in the poorly name CopyTask Task.

Ultimately I am just trying to figure out how to handle errors. Any guidance would help greatly. Thanks!

Answer 1

Found one error immediatelly:

try
{
    _ = RunCopy();
}

Must be awaited or the Try block can't capture any exceptions in the task. And BtnCopy_Click must become async.

private async void BtnCopy_Click(object sender, RoutedEventArgs e)
{
    Dispatcher.Invoke(() => { BtnBrowse.IsEnabled = false; BtnCopy.IsEnabled = false; });

    try
    {
      await RunCopy();
    }
    catch (Exception ex)
    {
      MessageBox.Show(ex.Message, "Error", MessageBoxButton.OK, MessageBoxImage.Error);
    }

    Dispatcher.Invoke(() => { BtnBrowse.IsEnabled = true; BtnCopy.IsEnabled = true; });