Perl code for Find and replace a tag value in XML

Question

Below is the XML I will be using:

<a>

<id>ABC</id>

<class />

<gender />

</a>

I want to write a Perl code which search for tag 'id' and replace the value "ABC" with "DEF".

However the nesting of above XML can change. So I want to make a generalized code that search for the tag 'id' independently of its exact position.

Till now i am able to get the logic where i can replace the value in ABC but that makes my code static of the position of tag 'id'.

#!usr/bin/perl
use warnings;
use XML::Simple;
use Spreadsheet::ParseExcel;
use Data::Dumper;
my $FileName = 'sample.xls';
my $xml_file = 'hello.xml';
$par=$ARGV[0];
my $xml = XMLin($xml_file,
    KeepRoot=>1,
    ForceArray=>1,);
$xml->{a}->[0]->{id}='DEF';
XMLout(
    $xml,
    KeepRoot =>1 ,
    NoAttr =>1,
    OutputFile => $xml_file,
        );
    }

Answer 1

XPath is able to find nodes without needing to know the position in the tree.

use strictures;
use XML::LibXML qw();
my $dom = XML::LibXML->load_xml(string => <<'XML');
<a>
<id>ABC</id>
<class />
<gender />
</a>
XML

for my $id ($dom->findnodes('//id[string()="ABC"]')) {
    $id->removeChildNodes;
    $id->appendText('DEF');
}

print $dom->toString