Question

Is it possible to create children using XmlDocument.CreateElement() and XmlNode.AppendChild() without specifying the namespace and have it use a “default” namespace?

Currently, if I create a root node with a namespace and don’t specify the namespace on the every childnode, the output xml will define a blank namespace.

Below is what is generated if I don’t specify the namespace for every element I create. Is there a shortcut where I don’t have to specify the namespace every time?

<root xmlns="http://example.com">
  <child1 xmlns="">
    <child2 />
  </child1>
</root>

Code:

XmlDocument doc = new XmlDocument();
var rootNode = doc.CreateElement("root", "http://example.com");
doc.AppendChild(rootNode);
var child1Node = doc.CreateElement("child1");
rootNode.AppendChild(child1Node);
var child2Node = doc.CreateElement("child2");
child1Node.AppendChild(child2Node);

Answer 1

If you have create your XML document, and you specify the same namespace for each element in the hierarchy – something like this:

        XmlDocument doc = new XmlDocument();

        const string xmlNS = "http://www.example.com";

        XmlElement root = doc.CreateElement("root", xmlNS);
        doc.AppendChild(root);

        XmlElement child1 = doc.CreateElement("child1", xmlNS);
        root.AppendChild(child1);

        child1.AppendChild(doc.CreateElement("child2", xmlNS));

        doc.Save(@"D:\test.xml");

then you’ll get this output file:

<root xmlns="http://www.example.com">
  <child1>
    <child2 />
  </child1>
</root>

The namespace on the <root> node is inherited down the hierarchy, unless the child elements define something else explicitly.

If you create a new XmlElement using doc.CreateElement and you don’t specify a XML namespace, then of course, that new element, will have a blank namespace and thus this will be serialized into that XML document you had.

I am not aware of any way to specify a default namespace to use whenever you’re creating a new element – if you specify one, the element will use that namespace – if you don’t specify one, it’s the blank namespace.