How do I add a namespace to an msxml DOMDocument? - winapi

Question

How do I add a schema to an IXMLDOMDocument?
For example, I want to generate the XML:
<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
<Relationship Id="rId1" Type="Frob" Target="Grob"/>
</Relationships>
I can construct the DOMDocument60 object (pseudo-code):
DOMDocument60 doc = new DOMDocument60();
IXMLDOMElement relationships = doc.appendChild(doc.createElement("Relationships"));
IXMLDOMElement relationship = relationships.appendChild(doc.createElement("Relationship"));
relationship.setAttribute("Id", "rId1");
relationship.setAttribute("Type", "Frob");
relationship.setAttribute("Target", "Grob");
Now comes the question of how to add the namespace.
How to add the namespace?
If I do the obvious solution, setting an attribute on the Relationships node called xmlns:
<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
through something like:
relationships.setAttribute("xmlns",
"http://schemas.openxmlformats.org/package/2006/relationships");
When the document is saved, it causes the resulting xml to be wrong:
<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
<Relationship Id="rId1" Type="Frob" Target="Grob" xmlns=""/>
</Relationships>
It places empty xmlns attributes on every other element. In this little test document it only misapplies the xmlns to one element. In the real world there are dozens, or a few million other elements with an empty xmlns attribute.
namespaceURI property
I tried setting the namespaceURI property of the Relationships element:
relationshps.namespaceURI := "http://schemas.openxmlformats.org/package/2006/relationships";
but the property is read-only.
schemas Property
The document does have a schemas property, which gets or sets an XMLSchemaCache object. But it requires an actual schema document. E.g. trying to just set a schema doesn't work:
schemas = new XMLSchemaCache60();
schemas.add('', 'http://schemas.openxmlformats.org/spreadsheetml/2006/main');
doc.schemas := schemas;
But that tries to actually load the schema url, rather than not loading the schema because it isn't a URI.
Perhaps I have to randomly try other things:
schemas = new XMLSchemaCache60();
schemas.add('http://schemas.openxmlformats.org/spreadsheetml/2006/main', null);
doc.schemas := schemas;
But that causes no xmlns to be emitted.
Rather than trying to build an XML document the correct way, I could always use a StringBuilder to build the XML manually, and then have parse it into an XML Document object.
But I'd rather do it the right way.

Answer 1

The trick is to realize the W3C DOM Level 2 and 3 have a method createElementNS 🕗:
Creates an element with the specified namespace URI and qualified name.
Syntax
element = document.createElementNS(namespaceURI, qualifiedName);
However MSXML 6 only supports DOM Level 1.
Fortunately, W3C DOM Level 1 did have a method to create an element with a namespace: createNode🕗:
Creates a node using the supplied type, name, and namespace.
HRESULT createNode(VARIANT Type, BSTR name, BSTR namespaceURI, out IXMLDOMNode node);
Thus my solution is that i have to change:
relationships: IXMLDOMElement = doc.createElement("Relationships");
into:
const NODE_ELEMENT: Integer = 1;
const ns: string = "http://schemas.openxmlformats.org/package/2006/relationships";
relationships: IXMLDOMElement = doc.createNode(NODE_ELEMENT, "Relationships", namespace);
A sucky part is that every element must be created in that namespace:
function AddElementNS(IXMLDOMNode parentNode, String tagName, String namespaceURI): IXMLDOMElement;
{
doc: IXMLDOMDocument = parentNode as IXMLDOMDocument;
if (doc == null)
doc = parentNode.ownerDocument;
if (namespaceURI <> "")
Result = doc.createNode(NODE_ELEMENT, tagName, namespaceURI)
else
Result = doc.createElement(tagName);
parentNode.appendChild(Result);
}
relationships: IXMLDOMElement = AddElementNS(doc, "Relationships", ns);
relationship: IXMLDOMElement = AddElementNS(relationships, "Relationship", ns);
relationship.setAttribute("Id", "rId1");
relationship.setAttribute("Type", "Frob");
relationship.setAttribute("Target", "Grob");
Bonus Reading
Creating XML with namespaces with Javascript and MSXML 🕗