Adding child nodes using c# Xdocument class

Question

I have an xml file as given below.

<?xml version="1.0" encoding="utf-8"?>
 <file:Situattion xmlns:file="test">

  <file:Properties>

</file:Situattion>

I would like to add the child element file:Character using xDocument.So that my final xml would be like given below

<?xml version="1.0" encoding="utf-8"?>
  <file:Situattion xmlns:file="test">

   <file:Characters>

     <file:Character file:ID="File0">
     <file:Value>value0</file:Value>
     <file:Description>
      Description0 
     </file:Description>
     </file:Character>

 <file:Character file:ID="File1">
     <file:Value>value1</file:Value>
     <file:Description>
     Description1
     </file:Description>
     </file:Character>

     </file:Characters>

Code in c# i tried using Xdocument class is given below.

        XNamespace ns = "test";
        Document = XDocument.Load(Folderpath + "\\File.test");

        if (Document.Descendants(ns + "Characters") != null)
        {

            Document.Add(new XElement(ns + "Character"));
        }
        Document.Save(Folderpath + "\\File.test");

At line "Document.Add(new XElement(ns + "Character"));", I am getting an error:

"This operation would create an incorrectly structured document.".

How can I add the node under "file:Characters".

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.