异步文件保存未正确执行 C#

Question

I've read up a bit on async and await and thought this would be the correct way to execute a file save asynchronously, but it still doesn't seem to be giving me the solution i'm looking for.

I have a program that when prompted will revert a photo to its original, unedited form. This involves an update in the database, followed by deleting the file from the directory and writing the new file to the directory to then be displayed. The problem that arises (to the best of my knowledge) is that it will update and then display before the file is completely written. This doesn't happen every time, but will display the old photo about 60% of the time and when refreshed, will show the correct photo. Here is the current (relevant) code I have for when the revert action happens.

 void RevertPhoto(object sender, EventArgs e)
 {
      //Update Database here

      HandleFileAsync();
 }
 async void HandleFileAsync()
    {
        Task<int> task = ResaveFile();
        int count = await task;
        if(count == 1)
        {
            Thread.Sleep(1000); //I put this in here to see if it'd fix the issue, but I feel like this shouldn't be necessary.
            PicturePlaceholder.Controls.Clear(); //Clear the pictures on the next page
            GetPhotoInfo(Convert.ToInt32(hiddenICTASKID.Value)); //Reload pictures on next page

            showPanels(PanelPhotoReview); //Show the panel while hiding the rest.
            hidePanels(PanelCleanList, PanelSiteList, PanelImageSwap, Panel5, PanelRevertPhoto, PanelImageDelete);
        }
    }

    async Task<int> ResaveFile()
    {
        await Task.Run(() =>
        {
            if (File.Exists(RevertFolderPath.Value)) //These two lines shouldn't be necessary as WriteAllBytes will overwrite.
                File.Delete(RevertFolderPath.Value);

            string filePath = RevertFolderPath.Value;
            File.WriteAllBytes(filePath, Convert.FromBase64String(Base64RevertImage.Value));
        });
        return 1;
    }

Is this the right way to approach it or am I quite a bit off?

Answer 1

Refactor your code to

async void RevertPhoto(object sender, EventArgs e)
 {
      //Update Database here

      await HandleFileAsync();
 }
 async Task HandleFileAsync()
    {
        await ResaveFile();


            PicturePlaceholder.Controls.Clear(); //Clear the pictures on the next page
            GetPhotoInfo(Convert.ToInt32(hiddenICTASKID.Value)); //Reload pictures on next page

            showPanels(PanelPhotoReview); //Show the panel while hiding the rest.
            hidePanels(PanelCleanList, PanelSiteList, PanelImageSwap, Panel5, PanelRevertPhoto, PanelImageDelete);

    }
     async Task ResaveFile()
        {
            await Task.Factory.StartNew(() =>
            {
                if (File.Exists(RevertFolderPath.Value)) //These two lines shouldn't be necessary as WriteAllBytes will overwrite.
                    File.Delete(RevertFolderPath.Value);

                string filePath = RevertFolderPath.Value;
                File.WriteAllBytes(filePath, Convert.FromBase64String(Base64RevertImage.Value));
            });
        }