XPath and TXmlDocument

Question

In Delphi XE is it possible to use XPath with a TXmlDocument component?

I'm aware I can use late binding to access the MSXML2 and then use XPath:

XML := CreateOleObject('MSXML2.DOMDocument.3.0') ;
XML.async := false;
XML.SetProperty('SelectionLanguage','XPath');

But I wanna know if TXmlDocument installed with Delphi XE supports XPath.

Cruces

+1 for a good question; it turned out to be harder than I expected to find an answer. – Rebbecarebbecca

Answer 1

I can't find anything in the TXMLDocument documentation about XPath.

XML example, from the OmniXML XPath demo:

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
  <book>
    <title lang="eng">Harry Potter</title>
  </book>
  <book>
    <title lang="eng">Learning XML</title>
  </book>
  <book>
    <title lang="slo">Z OmniXML v lepso prihodnost</title>
    <year>2006</year>
  </book>
  <book>
    <title>Kwe sona standwa sam</title>
  </book>
</bookstore>

Try something like this:

uses 
  XMLDoc, XMLDom, XMLIntf;

// From a post in Embarcadero's Delphi XML forum.
function 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;


var
  IDoc: IXMLDocument;
  INode: IXMLNode;
begin
  IDoc := LoadXMLDocument('.\books.xml');
  INode := SelectNode(IDoc.DocumentElement,'/bookstore/book[2]/title'); 
end;

Just as an FYI for others, I'll leave this in: OmniXML supports XPath, and has a demo that shows really well how to use it. It's also free, comes with source, supports Unicode, and has pretty good support through it's forums.

Rebbecarebbecca

Ken, many thnaks for your suggestion, but for now, I just want to know if is possible to use TXMLDocument with XPath, avoiding the use of the third party components. ;) – Cruces

@Salvador: Ok, if you insist. :) – Rebbecarebbecca

So how do we set the Search namespaces? ie, setProperty('SelectionNamespaces', SearchNS); – Alexisaley

@Robbie, I'm not sure. I haven't needed to do that, I'm afraid. You should post this as a new question of your own; you can always reference this answer as background (using the link available by right-clicking share below the answer and copying the link location). – Rebbecarebbecca

NOTE: Asked new question on that topic: #30688119 – Cerise

OmniXML has VERY limited support for XPath. Even to have simple X<>Y condition I had to patch the library. Kluug's OXML site has a speed shootout of some different XML libs for Delphi, so might be a starting point to explore alternatives. – Pelham