Question

I have this

XNamespace ns = "http://something0.com";
XNamespace xsi = "http://something1.com";
XNamespace schemaLocation = "http://something3.com";

XDocument doc2 = new XDocument(
    new XElement(ns.GetName("Foo"),
        new XAttribute(XNamespace.Xmlns + "xsi", xsi),
        new XAttribute(xsi.GetName("schemaLocation"), schemaLocation),
        new XElement("ReportHeader", GetSection()),
        GetGroup() 
    )
);

It gives

<?xml version="1.0" encoding="utf-8"?>
<Foo xmlns:xsi="http://something1.com"
xsi:schemaLocation="http://something3.com" 
xmlns="http://something0.com">
    <ReportHeader xmlns="">
        ...
    </ReportHeader>
    <Group xmlns="">
        ...
    </Group>
</Foo>

But I wan’t this result, how can it be done? (Notice the xmlns=""is missing..)

<?xml version="1.0" encoding="utf-8"?>
<Foo xmlns:xsi="http://something1.com"
xsi:schemaLocation="http://something3.com" 
xmlns="http://something0.com">
    <ReportHeader>
        ...
    </ReportHeader>
    <Group>
        ...
    </Group>
</Foo>

Answer 1

Your problem here is that you are setting the default namespace for the document to “http://something0.com”, but then appending elements that are not in this namespace – they are in the empty namespace.

Your document states it has a default namespace of xmlns=”http://something0.com”, but then you append elements which are in the empty namespace (because you didn’t supply their namespace when you appended them) – so they are all getting explicitly marked with xmlns=” to show they are not in the default namespace of the document.

This means there are two solutions to getting rid of the xmlns=””, but they have different meanings:

1) If you mean you definitely want the xmlns="http://something0.com" at the root element (specifying the default namespace for the document) – then to “disappear” the xmlns=”” you need to you need to supply this namespace when creating the elements:

// create a ReportHeader element in the namespace http://something0.com
new XElement(ns + "ReportHeader", GetSection())

2) If these elements are not meant to be in the namespace
“http://something0.com”, then you mustn’t add it as the default at
the top of the document (the xmlns=”http://something0.com” bit on
the root element).

XDocument doc2 = new XDocument(
     new XElement("foo",  // note - just the element name, rather  s.GetName("Foo")
          new XAttribute(XNamespace.Xmlns + "xsi", xsi),

The sample output you expect, suggests the former of these two choices.