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.

+1 for a good question; it turned out to be harder than I expected to find an answer. — Ken White, Mar 21 '11 at 23:12

score 15 · Accepted Answer · edited Dec 11 '12 at 13:00

15

~~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.

edited Dec 11 '12 at 13:00

bluish

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answered Mar 21 '11 at 21:54

Ken White

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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. ;) – Salvador Mar 21 '11 at 22:04
@Salvador: Ok, if you insist. :) – Ken White Mar 21 '11 at 22:21
So how do we set the Search namespaces? ie, setProperty('SelectionNamespaces', SearchNS); – Robbie Matthews Oct 05 '12 at 00:50
@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). – Ken White Oct 05 '12 at 01:02
NOTE: Asked new question on that topic: http://stackoverflow.com/questions/30687619/how-to-use-xpath-on-txmldocument-while-using-namespaces – Jerry Dodge Jun 06 '15 at 21:13
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. – Arioch 'The Sep 26 '16 at 14:27

XPath and TXmlDocument

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