Change NodeName of an XML tag element using MSXML

Question

I'd like to change the tag name of a MSXML XMLDOMElement, but unfortunately the nodeName property is read-only. Is there any straightforward way to do it, or have I to work around by doing some insert/replace and deep copy children?

<xml> ...
    <oldTagName>
      ... sub-elements
    </oldTagName>
<more xml> ...

Should become

<xml> ...
    <newTagName>
      ... sub-elements
    </newTagName>
<more xml> ...

Answer 1

According to Document Object Model you can't rename a node.

See: http://www.w3.org/TR/DOM-Level-2-Core/core.html#ID-1950641247

renameNode is possible in DOM Level 3 but not in MSXML library

Answer 2

This is "universal" rename node function (ObjectPascal) using MSXML interfaces, works fine and may be usable:

function RenameXMLTag(e: IXMLNode; NewName: WideString): IXMLNode;
var
 Doc : IXMLDocument;
 NewElem, NParent : IXMLNode;
 DNOld, DNNew : IDOMNode;
 AC : IXMLNodeList;
 i: Integer;
begin
  Doc := e.OwnerDocument;
  NewElem := Doc.CreateNode(NewName, e.NodeType);
  while e.HasChildNodes do
    NewElem.DOMNode.AppendChild(e.DOMNode.firstChild);
  AC := e.AttributeNodes;
  for i := 0 to AC.Count - 1 do
    NewElem.Attributes[AC[i].NodeName] := AC[i].NodeValue;
  NParent := e.ParentNode;
  DNOld := e.DOMNode;
  DNNew := NewElem.DOMNode;
  NParent.DOMNode.replaceChild(DNNew, DNOld);
  Result := NewElem;
end;

Answer 3

Just for reference, I ended up with a replace function which is copying all children to a newly created node: (VB6 sample code)

Private Sub ReplaceNodeName(oDoc As DOMDocument, oElement As IXMLDOMElement, newName As String)
    Dim ohElement As IXMLDOMElement
    Dim sElement As IXMLDOMElement
    Dim oChild As IXMLDOMNode

    ' search the children '
    If Not oElement Is Nothing Then
        Set ohElement = oElement.parentNode
        Set sElement = oDoc.createElement(newName)

        For Each oChild In oElement.childNodes
            Call sElement.appendChild(oChild)
        Next

        Call ohElement.replaceChild(sElement, oElement)
    End If
End Sub

Answer 4

This is my c++ version, maybe you will understand it easier:

#define SAFERELEASE(comobj) \
if (comobj)     \
{       \
 comobj->Release();  \
 comobj  = NULL;  \
}

void RenameElement(IXMLDOMElement * pElement, LPWSTR newName)
{
if (NULL == pElement)
    return;

IXMLDOMDocument * pParentDoc = NULL;
pElement->get_ownerDocument(&pParentDoc);

IXMLDOMElement * pNewElement = NULL;
pParentDoc->createElement(newName, &pNewElement);

VARIANT_BOOL bHasNodes;
pElement->hasChildNodes(&bHasNodes);

while (bHasNodes)
{
    IXMLDOMNode * pFirstChild = NULL;
    pElement->get_firstChild(&pFirstChild);
    pNewElement->appendChild(pFirstChild, NULL);
    pElement->hasChildNodes(&bHasNodes);
    SAFERELEASE(pFirstChild);
}
IXMLDOMNamedNodeMap * pAttrMap = NULL;
IXMLDOMNamedNodeMap * pAttrMapNew = NULL;
pElement->get_attributes(&pAttrMap);
pNewElement->get_attributes(&pAttrMapNew);
long nAttrLength = 0;
pAttrMap->get_length(&nAttrLength);
for (int n = 0; n < nAttrLength; n++)
{
    IXMLDOMNode * pListItem = NULL;
    pAttrMap->get_item(n, &pListItem);

    BSTR wsAttrName = NULL;
    pListItem->get_nodeName(&wsAttrName);

    BSTR wsAttrValue = NULL;
    pListItem->get_text(&wsAttrValue);

    IXMLDOMAttribute * pAttribute = NULL;
    pParentDoc->createAttribute((BSTR)wsAttrName, &pAttribute);
    pAttribute->put_value(CComVariant((BSTR)wsAttrValue));
    pAttrMapNew->setNamedItem(pAttribute, NULL);

    SAFERELEASE(pAttribute);
    SysFreeString(wsAttrValue);
    SysFreeString(wsAttrName);
    SAFERELEASE(pListItem);
}

IXMLDOMNode * pParent = NULL;
pElement->get_parentNode(&pParent);
pParent->replaceChild(pNewElement, pElement, NULL);

SAFERELEASE(pAttrMapNew);
SAFERELEASE(pAttrMap);
SAFERELEASE(pParent);
SAFERELEASE(pNewElement);
SAFERELEASE(pParentDoc);
}