How do I add a namespace when creating an XML file?

Question

I have to create an XML document in C#.

The root element has to look like this:

<valuation-request 
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xsi:noNamespaceSchemaLocation="valuations.xsd">

I'm using the following

XmlElement root = X.CreateElement("valuation-request");
root.SetAttribute("xmlns:xsi", "http://www.w3.org/2001/XMLSchema-instance");
root.SetAttribute("xsi:noNamespaceSchemaLocation", "valuations.xsd");

However this produces

<valuation-request 
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     noNamespaceSchemaLocation="valuations.xsd"> //missing the xsi:

What am I missing?

Answer 1

Use the overload of SetAttribute, that takes namespace as well:

root.SetAttribute("noNamespaceSchemaLocation", 
    "http://www.w3.org/2001/XMLSchema-instance", 
    "valuations.xsd"
);