convenientstore has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I am trying to learn and use XML with perl but because of difficulty that I am having with the perldoc XML::Twig and also the website of twig(despite all the tutorials, I decide to seek for help here. honestly, I just don't think I am getting it.

Anyway, I have fairly complicated XML file I want to parse out so that I can do some report on it but I am just not sure how to use XML::Twig nor if XML::Twig is even the right module to use.

I have been
1)trying to read the doc but honestly, it's little bit over my head...
2)trying to follow the tutorials on the website but it's not giving me what I want..(i am sure I am just not getting it .. same for 1) as well but
3)also did super seach on perlmonks w/ following key words ---> xml twig and read pretty much read all posts)

I have wrote a example xml file below and my question is, if I wanted to make a array of id so that my @array will contain qw/ msn movies espn/ how would I go about doing it?

I was thinking somehow using first_child method?
Would appreciate the pointer/advise.
thank you 
-------- code that I was just looking at-------------
#!/usr/bin/perl

use warnings;
use strict;

use XML::Twig;

my $twig = XML::Twig->new(twig_roots => { one => 1});
$twig->parsefile(shift);
$twig->print;




--- example file -------
<config>
 <one id="msn" type="shopping">
   <traffic>
       <daily value="on" />
       <weekly value="off" />
       <monthly value="off" />
   </traffic>
  </one>

 <one id="movies" type="entertainment">
   <traffic>
       <daily value="on" />
       <weekly value="off />
       <monthly value="on" />
   </traffic>
 </one>

 <one id="espn" type="sports">
  <traffic>
      <daily value="on" />
      <weekly value="on" />
      <monthly value="on />
      <hyper value="true />
  </traffic>
 </one>
</config>

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Re: trying to understand xml::twig and also trying to learn how to extract attribute
by GrandFather (Saint) on Nov 04, 2008 at 23:27 UTC

    You're not a long way away from what you need to do. twig_roots supplies a reference to a sub to handle matching elements. Consider:

    use warnings;
use strict;
use XML::Twig;

my $xmlStr = <<XML;
<config>
 <one id="msn" type="shopping">
   <traffic>
       <daily value="on" />
       <weekly value="off" />
       <monthly value="off" />
   </traffic>
  </one>

 <one id="movies" type="entertainment">
   <traffic>
       <daily value="on" />
       <weekly value="off" />
       <monthly value="on" />
   </traffic>
 </one>

 <one id="espn" type="sports">
  <traffic>
      <daily value="on" />
      <weekly value="on" />
      <monthly value="on" />
      <hyper value="true" />
  </traffic>
 </one>
</config>
XML

my $result = '';
my $twig = XML::Twig->new (twig_roots => {one => sub {oneHandler (\$re
+sult, @_);}});

$twig->parse ($xmlStr);
print $result;


sub oneHandler {
    my ($resRef, $twig, $elt) = @_;

    $$resRef = join ' ', $$resRef, $elt->att ('id');
    return;
}

    [download]

    Prints:

     msn movies espn

    [download]

    Note that there were a few missing close " in your sample XML that I've fixed.

    Also notice that I created an anonymous sub so I could pass extra parameters into the handler thus avoiding the need for global variables.

    Perl reduces RSI - it saves typing
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Re: trying to understand xml::twig and also trying to learn how to extract attribute
by toolic (Bishop) on Nov 05, 2008 at 01:43 UTC
    Here is a different approach using XML::Twig. I consider this a more brute-force, less elegant solution than that provided by GrandFather. However, it illustrates the TIMTOWTDI-ness of Twig; perhaps you are more comfortable thinking of this as looping through elements, rather than the more powerful use of handlers (as I currently am). I have borrowed GrandFather's cleaned up XML text. 
    use strict;
use warnings;
use Data::Dumper;
use XML::Twig;

my $xmlStr = <<XML;
<config>
 <one id="msn" type="shopping">
   <traffic>
       <daily value="on" />
       <weekly value="off" />
       <monthly value="off" />
   </traffic>
  </one>

 <one id="movies" type="entertainment">
   <traffic>
       <daily value="on" />
       <weekly value="off" />
       <monthly value="on" />
   </traffic>
 </one>

 <one id="espn" type="sports">
  <traffic>
      <daily value="on" />
      <weekly value="on" />
      <monthly value="on" />
      <hyper value="true" />
  </traffic>
 </one>
</config>
XML

my @ids;
my $t = XML::Twig->new();
$t->parse($xmlStr);
for my $one ($t->root()->children('one')) {
    push @ids, $one->att('id');
}
print Dumper(\@ids);

__END__

$VAR1 = [
          'msn',
          'movies',
          'espn'
        ];

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[d/l]

      I should have noted that the cleaned up XML is licensed under the Perl license so use it by all means. ;)

      Perl reduces RSI - it saves typing
[reply]
        thank you guys
        Grandfather's solution is *bit* above my head at this point
        But eventually, I like my code to look like that(once I have better understanding)
        so I tried the second solution with bit of modification, but the way I am doing is I am sure wrong(as it's not working)
        I wanted to loop through and find monthly value eq 'on' and then push a certain elements and attribute in the array which I can loop through later for usage...
        #!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;
use XML::Twig;

my $xmlStr = <<XML;
<config>
 <one id="msn" type="shopping">
   <traffic>
       <daily value="on" />
       <weekly value="off" />
       <monthly value="off" />
   </traffic>
  </one>

 <one id="movies" type="entertainment">
   <traffic>
       <daily value="on" />
       <weekly value="off" />
       <monthly value="on" />
   </traffic>
 </one>

 <one id="espn" type="sports">
  <traffic>
      <daily value="on" />
      <weekly value="on" />
      <monthly value="on" />
      <hyper value="true" />
  </traffic>
 </one>
</config>
XML

my @ids;
my $t = XML::Twig->new();
$t->parse($xmlStr);
for my $one (  ($t->root()->children('one')  ) {
    for my $month  (  ($t->root()->children('monthly')  ) {
           if ( $momth->att('value') eq 'on' ) {
                  push @ids, $one->att('id');
           }
    }
}
print Dumper(\@ids);

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