Re: Applying xPath to Xerces DOMDocument fails

["ovanes@t-online.de" <ov...@t-online.de>]

Sorry previous email was formatted as HTML and might be unreadable. Here
it is again in plain text format....


-- 
Ovanes Markarian

-----Original Message-----
Date: Thu, 17 Nov 2005 10:41:12 +0100
Subject: Applying xPath to Xerces DOMDocument fails
From: "ovanes@t-online.de" 
To: "Mailing List, Xalan-C" 

Hello,

I am relatively new to Xalan and somehow it drives me mad. I need to
apply an xPath to the pre-parsed XML document. The document is a
Xerces DOMDocument instance.

I read some postings on how to do that, but none of them worked. I
will try to summerize my efforts below:

I saw a post from Joerg Seidler:
http://marc.theaimsgroup.com/?l=xalan-c-users&m=108385669500218&w=2
and tried to do it in similar way, but with no luck.

My system configuration is:
Xerces-C 2.7.0
Xalan-C 1.10

May be I forgot some initialization or anything else.  Below are my
explanations:
1. Assume that Xerces-C and XPathEvaluator initializations succeeded.
And I have successfully parsed an XML document and have a DOMDocument
instance pointer to which I need xPath to be applied. xPath
expression was successfully tested for this document with XMLSpy and
Oxygen XML Editors (internally uses Xerces-J and Xalan-J). And the
selection always delivered the desired node. I extensively use
namespaces in my document and have my own namespace defined as
default namespace. I know that xPath 1.0 does not support default
namespaces that's why I also write a prefiexed xPath to the desired
element.

My code looks as follows:

//xtcxsl, xtcxml are defined as follows: 
/*
#ifdef XERCES_CPP_NAMESPACE
    namespace xtcxml=XERCES_CPP_NAMESPACE;
#else
    #define xtcxml
#endif    

#ifdef XALAN_CPP_NAMESPACE
    namespace xtcxsl=XALAN_CPP_NAMESPACE;
#else
    #define xtcxsl
#endif

*/

//assume that xPath is defined upon as XMLCh* or char*

xtcxsl::XMLSupportInit        xmlSupportInit;

xtcxsl::XercesDOMSupport     dom_support;
xtcxsl::XercesParserLiaison     parser_liaison(dom_support);

parser_liaison.setBuildWrapperNodes(true);
parser_liaison.setBuildMaps(true);

xtcxsl::XercesDOMWrapperParsedSource xSource(pDoc, parser_liaison,
dom_support); //xtcxml::DOMDocument* pDoc is defined upon.

xtcxsl::XalanDocument& xeDoc     = *xSource.getDocument();
xtcxsl::XalanElement* ns_node    = xeDoc.getDocumentElement();

xtcxsl::XPathEvaluator    evaluator;

xtcxsl::NodeRefList result;
//resulting list has no elements
evaluator.selectNodeList(result, dom_support, ns_node, xPath,
ns_node);
//node pointer is NULL
xtcxsl::XalanNode* node=evaluator.selectSingleNode(dom_support,
ns_node, xPath, ns_node);

Using command line sample SimpleXPathAPI with the sampe xml document
and xPath returns a valid node.

Can someone point me to what is wrong?

Many thanks!
-- 
Ovanes Markarian