Creating an XML element with a namespace with XmlDocument.CreateElement()

Question

I'm trying to create an XmlDocument using C# and .NET (version 2.0.. yes, version 2.0). I have set the namespace attributes using:

document.DocumentElement.SetAttribute(
    "xmlns:soapenv", "http://schemas.xmlsoap.org/soap/envelope");

When I create a new XmlElement using:

document.createElement("soapenv:Header");

...it doesn't include the soapenv namespace in the final XML. Any ideas why this happens?

More info:

Okay, I'll try to clarify this problem a bit. My code is:

XmlDocument document = new XmlDocument();
XmlElement element = document.CreateElement("foo:bar");
document.AppendChild(element); Console.WriteLine(document.OuterXml);

That outputs:

<bar />

However, what I want is:

<foo:bar />

Answer 1

You can assign a namespace to your bar element by using XmlDocument.CreateElement Method (String, String, String)

Example:

using System;
using System.Xml;

XmlDocument document = new XmlDocument();

// "foo"                    => namespace prefix
// "bar"                    => element local name
// "http://tempuri.org/foo" => namespace URI

XmlElement element = document.CreateElement(
    "foo", "bar", "http://tempuri.org/foo");

document.AppendChild(element);
Console.WriteLine(document.OuterXml);

Expected Output #1:

<foo:bar xmlns:foo="http://tempuri.org/foo" />

For a more interesting example, insert these statements before document.AppendChild(element);:

XmlElement childElement1 = document.CreateElement("foo", "bizz",
    "http://tempuri.org/foo");

element.AppendChild(childElement1);
    
XmlElement childElement2 = document.CreateElement("foo", "buzz",
    "http://tempuri.org/foo");

element.AppendChild(childElement2);

Expected Output #2:

<foo:bar xmlns:foo="http://tempuri.org/foo"><foo:bizz /><foo:buzz /></foo:bar>

Note that the child elements bizz and buzz are prefixed with the namespace prefix foo, and that the namespace URI http://tempuri.org/foo isn't repeated on the child elements since it is defined within the parent element bar.

Answer 2

using System;
using System.Xml;

namespace ConsoleApp3
{
    class Program
    {
        static void Main(string[] args)
        {
            var Ruta = @"C:\Users\isaac\Documents\XML\XMLTEST.xml";
            Agregar(Ruta, "32323");

        }

        public static void Agregar(string Ruta, string valor)
        {
            XmlDocument XML = new XmlDocument();

            XML.Load(Ruta);
            XmlNode root = XML.GetElementsByTagName("dte:DatosEmision")[0];

            string dte = "http://www.sat.gob.gt/dte/fel/0.2.0";
            XmlElement childElement = XML.CreateElement("dte", "Otros", dte);

            XmlElement childElement1 = XML.CreateElement("dte", "OtroTexto", dte);
            childElement1.SetAttribute("codigo", "OC");
            childElement1.InnerText = valor;
            ////
            childElement.AppendChild(childElement1);

            try
            {


                root.InsertAfter(childElement, root.LastChild);

            }
            catch (Exception x)
            {

                Console.WriteLine(x);
            }
            XML.Save("XMLFile2.xml");

        }
    }
}

as a result

    <dte:Otros>
      <dte:OtroTexto codigo="OC">32323</dte:OtroTexto>
    </dte:Otros>

Answer 3

Maybe you could share what you're expecting as final XML document.

However from what I understand you want to do that looks like:

    <?xml version="1.0"?>
    <soapMessage xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope">
        <Header xmlns="http://schemas.xmlsoap.org/soap/envelope" />
    </soapMessage>

so the code to do that would be:

    XmlDocument document = new XmlDocument();
    document.LoadXml("<?xml version='1.0' ?><soapMessage></soapMessage>");
    string soapNamespace = "http://schemas.xmlsoap.org/soap/envelope/";
    XmlAttribute nsAttribute = document.CreateAttribute("xmlns","soapenv","http://www.w3.org/2000/xmlns/");
    nsAttribute.Value = soapNamespace;
    document.DocumentElement.Attributes.Append(namespaceAttribute);
    document.DocumentElement.AppendChild(document.CreateElement("Header",soapNamespace));