将RichText文档保存到Windows Store应用程序中的temp文件夹中

Question

I'm trying to save the content of a RichEditBox to my apps temporary folder, but I can't get it to work.

Here's the working code to save the file to disk, through the Save File picker:

// [code for savePicker. Not relevant because that all works fine]
StorageFile file = await savePicker.PickSaveFileAsync();
IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite);
editor.Document.SaveToStream(TextGetOptions.FormatRtf, stream);

Here's the working code to save a txt file to the temp storage

StorageFolder temp = ApplicationData.Current.TemporaryFolder;
StorageFile file = await temp.CreateFileAsync("temp.txt", 
                         CreationCollisionOption.ReplaceExisting);
await FileIO.WriteTextAsync(file, "some text");

So when I combined these to save RTF content to the temp folder, this is what I wrote:

StorageFolder temp = ApplicationData.Current.TemporaryFolder;
StorageFile file = await temp.CreateFileAsync("temp.rtf", 
                         CreationCollisionOption.ReplaceExisting);
IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite);
editor.Document.SaveToStream(TextGetOptions.FormatRtf, stream);

This doesn't work. I get an Access Denied error (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED)) on the second line StorageFile file = etc . However this same line of code executes fine in the second block above. It seems that when I follow it with file.OpenAsync it throws an error. Can someone point me in the right direction here? Is it something to do with await ?

EDIT: I've accepted and upvoted the answer by Damir Arh, as it is the correct fix to this issue. My workaround solved the issue for me, but Damir Arh's answer addresses the root cause of the issue which is always better of course.

Answer 1

This block of code should work just fine; I even tested it, just to be sure:

StorageFolder temp = ApplicationData.Current.TemporaryFolder;
StorageFile file = await temp.CreateFileAsync("temp.rtf", 
                         CreationCollisionOption.ReplaceExisting);
IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite);
editor.Document.SaveToStream(TextGetOptions.FormatRtf, stream);

You have incorrectly identified, why it was failing. CreateFileAsync can't fail because it is followed by OpenAsync ; the latter didn't even start executing when it failed.

The most probable reason was that you already had it open from a Stream that you didn't close properly. This can still happen even with the code that you have posted in the answer.

I would suggest you use CreationCollisionOption.GenerateUniqueName instead of CreationCollisionOption.ReplaceExisting . This way a file with a different name will be created if for some reason it can't be with the original file name.

Also make sure you're properly closing the stream once you're done with writing. Since IRandomAccessStream implements IDisposable , you should always call Dispose on it when you don't need it any more. Or even better: put it in a using block which will do this for you.

Here's the code with these two changes applied:

StorageFolder temp = ApplicationData.Current.TemporaryFolder;
StorageFile file = await temp.CreateFileAsync("temp.rtf",
                            CreationCollisionOption.GenerateUniqueName);
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
    Editor.Document.SaveToStream(TextGetOptions.FormatRtf, stream);
    await stream.FlushAsync();
}

Answer 2

I've figured out a workaround:

StorageFolder temp = ApplicationData.Current.TemporaryFolder;
StorageFile file = await temp.CreateFileAsync("temp.rtf", 
                         CreationCollisionOption.ReplaceExisting);
string rtfcontent = "";
editor.Document.GetText(TextGetOptions.FormatRtf, out rtfcontent);
await FileIO.WriteTextAsync(file, rtfcontent);