How to write the contents of a Onedrive<Item> to a local file

Question

In my app, I am using OneDrive to keep data in sync. I am successfully writing the file to OneDrive, but am having no luck replacing the local outdated data with the newer OneDrive data.

My current method, which completes without throwing an exception, does not return the same text data that the file on OneDrive contains. Goal of the method is to compare the datemodified to the OneDrive file to the local file, and if OneDrive is newer, write the contents of the OndeDrive file to the local StorageFile, and then return it to be de-serialized.

private async Task<string> GetSavedDataFileAsync(string filename)
    {
        string filepath = _appFolder + @"\" + KOWGame + @"\" + filename;
        StorageFile localread;
        BasicProperties localprops = null;
        string txt;
        try
        {
            localread = await local.GetFileAsync(filepath);
            localprops = await localread.GetBasicPropertiesAsync();
        }
        catch (FileNotFoundException)
        { localread = null; }
        if (_userDrive != null)
        {
            if (_userDrive.IsAuthenticated)
            {
                try
                {
                    Item item = await _userDrive.Drive.Special.AppRoot.ItemWithPath(filepath).Request().GetAsync();
                    if (item != null)
                    {
                        DateTimeOffset drivemodified = (DateTimeOffset)item.FileSystemInfo.LastModifiedDateTime;
                        if (localprops != null)
                        {
                            if (drivemodified > localprops.DateModified)
                            {
                                Stream stream = await localread.OpenStreamForWriteAsync();
                                using (stream)
                                { await _userDrive.Drive.Special.AppRoot.ItemWithPath(filepath).Request().GetAsync(); }
                            }
                        }
                    }
                }
                catch (OneDriveException e)
                {
                    if (e.IsMatch(OneDriveErrorCode.ActivityLimitReached.ToString()))
                    { string stop; }
                }
            }
        }
        if (localread == null) return string.Empty;
        txt = await FileIO.ReadTextAsync(localread);
        return txt;
    }

I tried to reverse engineer another answer I found on Stack regarding writing a StorageFile to OneDrive, in that I needed to open the stream of the local file, but I doesn't appear to be working properly.

Answer 1

To get the content of a OneDrive item, we need use following method:

var contentStream = await _userDrive.Drive.Special.AppRoot.ItemWithPath(filepath).Content.Request().GetAsync();

While using

await _userDrive.Drive.Special.AppRoot.ItemWithPath(filepath).Request().GetAsync();

you are getting the OneDrive Item not its content.

So you can change your code like following to write the content of a Onedrive item to a local file:

if (drivemodified > localprops.DateModified)
{
    using (var stream = await localread.OpenStreamForWriteAsync())
    {
        using (var contentStream = await _userDrive.Drive.Special.AppRoot.ItemWithPath(filepath).Content.Request().GetAsync())
        {
            contentStream.CopyTo(stream);
        }
    }
}