Question

I am downloading a xml file from the internet and save it in isolated storage. If I try to read it I get an error:

Data at the root level is invalid. Line 1, position 1.

string tempUrl = "http://xxxxx.myfile.xml"; // changed
WebClient client = new WebClient();
client.OpenReadAsync(new Uri(tempUrl));
client.OpenReadCompleted += new OpenReadCompletedEventHandler(delegate(object sender, OpenReadCompletedEventArgs e) {

StreamWriter writer = new StreamWriter(new IsolatedStorageFileStream("myfile.xml", FileMode.Create, FileAccess.Write, myIsolatedStorage));
 writer.WriteLine(e.Result);
 writer.Close();
});

This is how I download and save the file…

And I try to read it like that:

IsolatedStorageFileStream fileStream = myIsolatedStorage.OpenFile("myfile.xml", FileMode.Open, FileAccess.Read);
XDocument xmlDoc = XDocument.Load(fileStream);

This is where I get the error…

I have no problem reading the same file without downloading and saving it to isolated storage… so there must be the fault.

Answer 1

This:

writer.WriteLine(e.Result);

doesn’t do what you think it does. It’s just calling ToString() on a Stream, and writing the result to a file.

I suggest you avoid using a StreamWriter completely, and simply copy from e.Result straight to the IsolatedStorageFileStream:

using (var output = new IsolatedStorageFileStream("myfile.xml", FileMode.Create, 
                                    FileAccess.Write, myIsolatedStorage))
{
    CopyStream(e.Result, output);
}

where CopyStream would be a method to just copy the data, e.g.

public static void CopyStream(Stream input, Stream output)
{
    byte[] buffer = new byte[8 * 1024];
    int read;
    while((read = input.Read (buffer, 0, buffer.Length)) > 0)
    {
        output.Write (buffer, 0, read);
    }
}