R – How to add child elements to XML using Perl’s XML::Twig

perlxmlxml-twig

I have the following XML file:

<SOURCE_SERVER>
  <SERVER HOSTNAME="serv1">
      <CIFS_SERVICE NETBIOSNAME="serv1"/>
  </SERVER>
  <SERVER HOSTNAME="serv2">
  </SERVER>
<SOURCE_SERVER>

Now, I want to add child <CIFS_SERVICE NETBIOSNAME="serv2"/> to <SERVER HOSTNAME="serv2">. How do I do this using XML::Twig?

Best Answer

Here is a solution incorporating what I think are reasonable fixes to your question. The code below is based on the filtering example given in the documentation.

#!/usr/bin/perl

use strict;
use warnings;

use XML::Twig;

my $t = XML::Twig->new(
    twig_roots => { SERVER => \&update },
    twig_print_outside_roots => 1,
);

$t->parse(\*DATA);

sub update {
    my ($t, $server) = @_;
    if ( 'serv2' eq $server->att('HOSTNAME') ) {
        $server->insert(
            CIFS_SERVICE => { NETBIOSNAME => 'serv2' },
        );
    }
    $server->print;
}


__DATA__
<SOURCE_SERVER>
  <SERVER HOSTNAME="serv1">
      <CIFS_SERVICE NETBIOSNAME="serv1" />
  </SERVER>
  <SERVER HOSTNAME="serv2">
  </SERVER>
</SOURCE_SERVER>

Output:

C:\Temp> x
<SOURCE_SERVER>
  <SERVER HOSTNAME="serv1"><CIFS_SERVICE NETBIOSNAME="serv1"/></SERVER>
  <SERVER HOSTNAME="serv2"><CIFS_SERVICE NETBIOSNAME="serv2"/></SERVER>
</SOURCE_SERVER>

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R – How to add an attribute to a child element using Perl’s XML::Twig

As Jon hinted to you, you have a syntax error in the code you posted. You should have seen a compile error like:

syntax error at test line 18, near "->set_att{" Execution of program.pl aborted due to compilation errors.

However, you might have typed the code into your answer so that code doesn't match what you are actually doing. Always put the actual code into your question rather than re-typing it, and always post a full program when you can. When you post your program, I don't have to start from scratch to debug what I think you might be doing. :)

Here's a program that does what you want:

use XML::Twig;

my $xml = <<'XML';
<DATA>
   <CHILD_DATA ATVAL="value1"/>
   <CHILD_DATA />
</DATA>
XML

my $twig= XML::Twig->new( keep_spaces => 1 );

$twig->parse( $xml );

$twig
    ->root
    ->last_child('CHILD_DATA')
    ->set_att("ATVAL" => "value2");

$twig->flush;

Best Answer

Related Solutions

C# – How to save application settings in a Windows Forms application

R – How to add an attribute to a child element using Perl’s XML::Twig

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