Title: Select Single IXMLNode / TXmlNode Using XPath In Delphi's XmlDom
Previous tip, XPath To Select XML Nodes , provided an XPath wrapper to select a collection of IXMLNodes using their name.
The XPath's selectNodes (xmldox.pas IDomNodeSelect.selectNodes) function selects a list of nodes matching the XPath expression.
To select the first node that matches the XPath expression you can use the selectNode function of the IDomNodeSelect defined in XmlDom.pas.
Here's how to get the IXMLNode (TXMLNode) by wrapping the call to XPath's selectNode:
class function TXMLNodeHelper.SelectNode(xnRoot: IXmlNode; const nodePath: WideString): IXmlNode;
var
intfSelect : IDomNodeSelect;
dnResult : IDomNode;
intfDocAccess : IXmlDocumentAccess;
doc: TXmlDocument;
begin
Result := nil;
if not Assigned(xnRoot)
or not Supports(xnRoot.DOMNode, IDomNodeSelect, intfSelect) then
Exit;
dnResult := intfSelect.selectNode(nodePath);
if Assigned(dnResult) then
begin
if Supports(xnRoot.OwnerDocument, IXmlDocumentAccess, intfDocAccess) then
doc := intfDocAccess.DocumentObject
else
doc := nil;
Result := TXmlNode.Create(dnResult, nil, doc);
end;
end;
Note: the above is a class function.
Note: a full examination of XPath and its usage is, of course, beyond the scope of this article.