Namespace declarations in XElement may be inconsistent

[nathan130200]

Basically if we implicitly declare the default namespace of the XElement, we cannot access it through the GetDefaultNamespace() function, which returns XNamespace.None, which is incorrect, since the namespace has already been defined in the current scope and there is no way to change the namespace without having to recursively clone the entire XML tree...

Consider the code below:

using System;
using System.Xml.Linq;

var el = new XElement("{urn:sharplab:io}root");

Console.WriteLine(" ------------ Construct ------------");

// should not be empty. namespace is declared in this scope...
Console.WriteLine("default namespace: " + el.GetDefaultNamespace());

// fine
Console.WriteLine("namespace: " + el.Name.Namespace);
Console.WriteLine("xml: " + el);



el = XElement.Parse(el.ToString());

Console.WriteLine("\n ------------ Parse ------------");
// not empty now, correct behaviour. because xmlns is declared in this scope but now its just add XAttribute to it.
Console.WriteLine("default namespace: " + el.GetDefaultNamespace());

// fine
Console.WriteLine("namespace: " + el.Name.Namespace);
Console.WriteLine("xml: " + el);

SharpLab

As you can see, when creating the XElement, it does not consider the problem with the XElement as a valid value for GetDefaultNamespace, which is that it considers ONLY what is linked to the XName and it does not make sense.

Since what defines the namespace is the URI that qualifies it, if it has a prefix, this prefix determines the scope of the URI. So what should say which namespace the XElement has is the xmlns or xmlns:prefix attribute and not the XName.Namespace property.

I've even opened an issue with this problem before, but since almost a month have passed without any response from anyone, I ended up choosing to close it. But I had to do some projects that use and need XML without having to rewrite the entire DOM mechanism, I encountered this same problem with Namespaces again.