Hi all,I have a UDF in Java that does some XML processing. My parser works
fine. I am now adding some code to this UDF that uses XPath. However, my XPath
expression always returns null. I wrote another standalone program that has the
same path expression and same document as its input, I get correct results.
However, my Pig UDF with same XPath expression and same i/p it retunes a null
result. Please find relevant code snippet attached. Has anyone used XPath in
UDFs. Also I saw mention of XPath with PiggyBan, but my 0.11 code does not have
that in its contrib area. Does anyone has any experience with using that?
public parseXml (String xmlRecords){/* I have a sequence file so xmlRecords isn
basically the xml file to parse */
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setNamespaceAware(true); db =
DocumentBuilderFactory.newInstance().newDocumentBuilder();InputSource is = new
InputSource();is.setCharacterStream(new StringReader(xmlRecords));doc =
db.parse(is);
// other code….
} public String tokenIdToStringXPath (String tokenidstr) {
String querystr = "//lang:Token[@xml:id='" + tokenidstr + "']";
Element tokenelem = null; String resultingtokenstr = "Sameer";
StringBuilder resultstr = new StringBuilder();
try {
XPathExpression expr = xPath.compile(querystr);
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
resultstr.append("Querystr: " + querystr);
resultstr.append(" ::Nodes: " + nodes.getLength());
}
The XPath expression after evaluation never
//lang:Token[@xml:id='639'] ::Nodes: 0
