xml parsing and string manipulation using perl - perl

Question

I have an xml file with many lines similar to :
<parameter element="XYZ" module="XYZ" parametername="MyParameter" moc="MyParameter" moi="ABC=1473,DEF=0,GHI=0,JKL=0 />
My requirements are :
If the moc and parametername are same convert the first character in the parametername to lower case.
Reverse the moi like below.
So the converted line should be like :
<parameter element="XYZ" module="XYZ" parametername="myParameter" moc="MyParameter" moi="JKL=0,GHI=0,DEF.dEF=0,ABC.aBC=1473 />

Answer 1

Using XML::LibXML and adding a new element for a complete example (and assuming the changes are to be made on an element called parameter):
use strict;
use warnings;
use XML::LibXML;
my $dom = XML::LibXML->load_xml(string => <DATA>);
for my $node($dom->findnodes('//parameter')) {
my $param = $node->getAttribute('parametername');
my $moc = $node->getAttribute('moc');
my #moi = split ",", $node->getAttribute('moi');
$node->setAttribute('parametername', lcfirst $param) if $param eq $moc;
$node->setAttribute('moi', join ',', reverse #moi);
}
print $dom;
__DATA__
<root>
<parameter element="XYZ" module="XYZ" parametername="MyParameter" moc="MyParameter" moi="ABC=1473,DEF=0,GHI=0,JKL=0"/>
<parameter element="XYZ" module="XYZ" parametername="foo" moc="MyParameter" moi="XYZ=1473,DEF=0,GHI=0,JKL=0"/>
</root>
Result:
<root>
<parameter element="XYZ" module="XYZ" parametername="myParameter" moc="MyParameter" moi="JKL=0,GHI=0,DEF=0,ABC=1473"/>
<parameter element="XYZ" module="XYZ" parametername="foo" moc="MyParameter" moi="JKL=0,GHI=0,DEF=0,XYZ=1473"/>
</root>
Other ways to load_xml file using XML::LibXML

Answer 2

use strict;
use warnings;
use 5.014;
use XML::LibXML;
my $filename = "xml.xml";
my $parser = XML::LibXML->new();
my $doc = $parser->parse_file($filename);
say $doc;
for my $param ($doc->findnodes('//parameter')) {
my $pname_attr = $param->getAttribute('parametername');
my $moc_attr = $param->getAttribute('moc');
if ($pname_attr eq $moc_attr) {
$param->setAttribute('parametername', lcfirst $pname_attr);
my $moi_attr = $param->getAttribute('moi');
my #pieces = split ',', $moi_attr;
$pieces[0] =~ s/\A([^=]+)/$1.\l$1/xms;
$pieces[1] =~ s/\A([^=]+)/$1.\l$1/xms;
$param->setAttribute('moi', join ',', reverse #pieces);
}
}
say $doc;
--output:--
<?xml version="1.0" encoding="UTF-8"?>
<root>
<parameter element="XYZ" module="XYZ" parametername="ABC" moc="CBA" moi="ABC=1473,DEF=0,GHI=0,JKL=0"/>
<parameter element="XYZ" module="XYZ" parametername="MyParameter" moc="MyParameter" moi="ABC=1473,DEF=0,GHI=0,JKL=0"/>
</root>
<?xml version="1.0" encoding="UTF-8"?>
<root>
<parameter element="XYZ" module="XYZ" parametername="ABC" moc="CBA" moi="ABC=1473,DEF=0,GHI=0,JKL=0"/>
<parameter element="XYZ" module="XYZ" parametername="myParameter" moc="MyParameter" moi="JKL=0,GHI=0,DEF.dEF=0,ABC.aBC=1473"/>
</root>
If you want to change the moi attribute in all the <parameter> tags, then the code would look like this:
...
...
for my $param ($doc->findnodes('//parameter')) {
my $pname_attr = $param->getAttribute('parametername');
my $moc_attr = $param->getAttribute('moc');
if ($pname_attr eq $moc_attr) {
$param->setAttribute('parametername', lcfirst $pname_attr);
}
my $moi_attr = $param->getAttribute('moi');
my #pieces = split ',', $moi_attr;
$pieces[0] =~ s/\A([^=]+)/$1.\l$1/xms;
$pieces[1] =~ s/\A([^=]+)/$1.\l$1/xms;
$param->setAttribute('moi', join ',', reverse #pieces);
}
Response to comments:
1)
When I run it it says >/usr/bin/perl edit_mpvl.pl Perl v5.14.0
required--this is only v5.10.0,
Change the line:
use 5.014;
to:
use 5.010;
2)
Can we write the output to a file
Sure, add this:
my $fname = 'modified.xml';
open my $OUTFILE, '>', $fname
or die "Couldn't open $fname: $!";
print {$OUTFILE} $doc->toString;
close $OUTFILE;
Or, you can pretty print like this:
...
...
use XML::LibXML::PrettyPrint;
use Readonly;
...
...
Readonly my $SPACE => " ";
my $pp = XML::LibXML::PrettyPrint->new(
indent_string => $SPACE x 4 #Replace 4 by the number of spaces you want the indenting to be.
);
$pp->pretty_print($doc); #modifies $doc inplace
print {$OUTFILE} $doc->toString;
close $OUTFILE;