Adding child nodes using c# Xdocument class

Question

I have an xml file as given below.

Answer 1

You're trying to add an extra file:Character element directly into the root. You don't want to do that - you want to add it under the file:Characters element, presumably.

Also note that Descendants() will never return null - it will return an empty sequence if there are no matching elements. So you want:

var ns = "test";
var file = Path.Combine(folderPath, "File.test");
var doc = XDocument.Load(file);
// Or var characters = document.Root.Element(ns + "Characters")
var characters = document.Descendants(ns + "Characters").FirstOrDefault();
if (characters != null)
{
    characters.Add(new XElement(ns + "Character");
    doc.Save(file);
}

Note that I've used more conventional naming, Path.Combine, and also moved the Save call so that you'll only end up saving if you've actually made a change to the document.