in reply to XML parsing problem

In the chatterbox the OP said he is trying to use XML::Simple as he does not understand XML::Twig. Please allow me to show an XML::Twig example in case he changes his mind. 

use warnings; use strict;
use XML::Twig;
my $twig = XML::Twig->new;
$twig->parse(*DATA);
for my $query ($twig->findnodes("/queries/query")) {
    my $name = $query->field("name");
    my $topN = $query->field("topN");
    print "query name=($name) topN=($topN)\n";
}
__DATA__
<?xml version='1.0'?>
<queries>
    <query>
        <name>topHosts</name>
        <layer>LINK</layer>
        <topN>20</topN>
        <datatype>topHosts</datatype>
        <filter></filter>
    </query>
    <query>
        <name>topHosts</name>
        <layer>LINK</layer>
        <topN>120</topN>
        <datatype>topHosts</datatype>
        <filter></filter>
    </query>
</queries>

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Re^2: XML parsing problem
by runrig (Abbot) on Mar 10, 2009 at 20:25 UTC
    And here's an XML::Rules example:
    #!/usr/bin/perl

use strict;
use warnings;

use XML::Rules;

my @rules = (
  _default => sub {$_[0] => $_[1]->{_content}},
  query =>    sub { print "$_[1]->{name}: $_[1]->{topN}\n" },
);
my $r = XML::Rules->new(rules => \@rules);
$r->parse(\*DATA);

__END__
<?xml version='1.0'?>
<queries>
    <query>
        <name>topHosts</name>
        <layer>LINK</layer>
        <topN>20</topN>
        <datatype>topHosts</datatype>
        <filter></filter>
    </query>
    <query>
        <name>topHosts</name>
        <layer>LINK</layer>
        <topN>120</topN>
        <datatype>topHosts</datatype>
        <filter></filter>
    </query>
</queries>

    [download]
    Here's an alternate example:
    use strict;
use warnings;

use XML::Rules;
use Data::Dumper qw(Dumper);

my @rules = (
  _default => 'content',
  # Default filter to 'None' (v5.10 syntax here)
  filter   => sub { $_[1]{_content} //= 'None'; $_[0] => $_[1]{_conten
+t} },
  query    =>    'no content array',
  queries  => 'pass no content',
);
my $r = XML::Rules->new(rules => \@rules);
my $data = $r->parse(\*DATA); # Assume same data as above
print Dumper $data;

# Output
$VAR1 = {
          'query' => [
                     {
                       'topN' => '20',
                       'layer' => 'LINK',
                       'filter' => 'None',
                       'name' => 'topHosts',
                       'datatype' => 'topHosts'
                     },
                     {
                       'topN' => '120',
                       'layer' => 'LINK',
                       'filter' => 'None',
                       'name' => 'topHosts',
                       'datatype' => 'topHosts'
                     }
                   ]
        };

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      And what would an XML-thread be without the third blind mouse; XML::LibXML. 

      use XML::LibXML;
my $parser = XML::LibXML->new();
my $doc = $parser->parse_file("query.xml");

for my $query ( $doc->findnodes("//queries/query") )
{
    for my $kid ( $query->findnodes("*") )
    {
        printf("%10s : %s\n",
               $kid->getName,
               $kid->textContent
               );
    }
    print "\n";
}

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