perl script to iterate over xml nodes using XML::LibXML - perl

Question

I am trying to come up with a perl script to iterate over some nodes and get values in xml file.
My XML File looks like below and is saved spec.xml
<?xml version="1.0" encoding="UTF-8"?>
<WO xmlns="http://www.example.com/yyyy" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
<WOSet>
<SR>
<FINISHTIME>2013-07-29T18:21:38-05:00</FINISHTIME>
<STARTTIME xsi:nil="true" />
<TYPE>SR</TYPE>
<DESCRIPTION>Create CUST</DESCRIPTION>
<EXTERNALSYSTEMID />
<REPORTEDBY>PCAUSR</REPORTEDBY>
<REPORTEDEMAIL />
<STATUS>RESOLVED</STATUS>
<SRID>1001</SRID>
<UID>1</UID>
<SPEC>
<AVALUE>IT</AVALUE>
<ATTRID>CUST_DEPT</ATTRID>
<NALUE xsi:nil="true" />
<TVALUE />
</SPEC>
<SPEC>
<AVALUE>001</AVALUE>
<ATTRID>DEPT_CODE</ATTRID>
<NVALUE xsi:nil="true" />
<TVALUE />
</SPEC>
</SR>
</WOSet>
</WO>
when I run the below script , I neither get the output nor any error to get clue on where to fix things...
I am not a perl expert , would love experts here to through some light...
#!/usr/bin/perl
use XML::LibXML;
use strict;
use warnings;
my $file = 'spec.xml';
my $parser = XML::LibXML->new();
my $tree = $parser->parse_file($file);
my $root = $tree->getDocumentElement;
foreach my $atrid ( $tree->findnodes('WO/WOSet/SR/SPEC') ) {
my $name = $atrid->findvalue('ATTRID');
my $value = $atrid->findvalue('AVALUE');
print $name
print " = ";
print $value;
print ";\n";
}
My expected output is
CUST_DEPT = IT
DEPT_CODE = 001

Answer 1

The XML doesn't contain any element named WO in the null namespace. You want to match the elements named WO in the http://www.example.com/yyyy namespace.
#!/usr/bin/perl
use strict;
use warnings;
use XML::LibXML qw( );
use XML::LibXML::XPathContext qw( );
my $file = 'spec.xml';
my $parser = XML::LibXML->new();
my $doc = $parser->parse_file($file);
my $root = $doc->getDocumentElement;
my $xpc = XML::LibXML::XPathContext->new($doc);
$xpc->registerNs(y => 'http://www.example.com/yyyy');
for my $atrid ( $xpc->findnodes('y:WO/y:WOSet/y:SR/y:SPEC') ) {
my $name = $xpc->findvalue('y:ATTRID', $atrid);
my $value = $xpc->findvalue('y:AVALUE', $atrid);
print "$name = $value\n";
}