rainforest1155 has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks,

I'm new to Perl and was trying to extract the contents of a specific tag from my VLC webserver xml status page. Here's an example of the XML (I removed a couple of tags in the sections I'm not interested in to keep things shorter:

<root>
  <fullscreen>0</fullscreen>
  <audiodelay>0</audiodelay>
  <apiversion>3</apiversion>
  <time>1</time>
  <volume>256</volume>
  [...]
  <information>
    <category name="meta">
      <info name="title">CINEMIX</info>
      <info name="filename">CINEMIX</info>
      <info name="genre">Soundtracks Classical New Age</info>
      <info name="now_playing">John Williams-Losing E.T.-E.T. The Extr
+a-Terrestrial: 20th Anniversary</info>
    </category>
    <category name="Stream 0">
      <info name="Bitrate">192 kb/s</info>
      [...]
    </category>
  </information>
  <stats>
    <lostabuffers>2</lostabuffers>
    [...]
  </stats>
</root>

[download]

What I'm interested in is just the contents of the <info name="now_playing"> tag which contains artist, title and album.

I already have some code that does return all the <info> tags but I'm not sure how to specifically return just the "now_playing" tag content.

This is the code I managed to hack together so far using parts of code I found in the monastry:

#!/usr/bin/perl
 
use strict;
use XML::Rules;
use LWP::Simple;

my $streaminfo = get("http://127.0.0.1:8080/requests/status.xml"); 
  
my $parser = XML::Rules->new(
    stripspaces => 7,
    rules => {
        info => sub {
            print "$_[1]->{_content}\n";
            return;
        },
    }
);

[download]

I haven't been able to figure out how to filter the results to just the portion I'm interested to. I did look at the XML::Parser docs on cpan.org and have the feeling it's in there, especially the home / office phone example that's touched on in the synopsis, but I can't translate that into any working code.

Thanks for any assistance you can offer.

Sebastian

Replies are listed 'Best First'.
Re: extract tag content from VLC webserver via XML::Rules
by vagabonding electron (Curate) on Jun 25, 2013 at 11:32 UTC

    Keeping your code as is your could just change this part:

    my $parser = XML::Rules->new(
    stripspaces => 7,
    rules => {
        info => sub {
            print "$_[1]->{_content}\n" 
            if $_[1]->{name} eq 'now_playing'; # <-
            return;
        },
    }
);
$parser->parse( $xml);

    [download]

    which prints for me in your example:

    John Williams-Losing E.T.-E.T. The Extra-Terrestrial: 20th Anniversary

    [download]
[reply]
[d/l]
[select]

      Sweet, that's exactly what I was looking for!

      Thanks for the regex suggestions as well. I was actually trying the regex route before but it's something I haven't much luck with wrapping my head around so far.

      Love the super fast replies here. You guys are great.

[reply]

        Okay, I'm stuck again. I can print the now_playing content just fine, but that's not really my intention. I would like to use the data further down the line, but can't seem to get it out of the XML-Rules parser section.

        I tried to populate a string called $nowplaying with it but outside of the parser section, the string prints just empty. Obviously, the print is again just temporary so I can see that it works before I continue.

        How do I get the string contents outside of the parser section? Here's what I have:

        my $nowplaying = "";

my $parser = XML::Rules->new(
    stripspaces => 7,
    rules => {
        info => sub {
            $nowplaying = $_[1]->{_content} 
            if $_[1]->{name} eq 'now_playing';
            return ;
        }
    }
);
$parser->parse($streaminfo);

print $nowplaying;

        [download]

        I'm sure it's again something real simple I'm missing here.

[reply]
[d/l]
Re: extract tag content from VLC webserver via XML::Rules
by hdb (Monsignor) on Jun 25, 2013 at 09:42 UTC

    If really all you want is that one item and it is on one line of your XML file, use a regex: 

    /^\s*<info name="now_playing">(.*?)<\/info>$/

    [download]
[reply]
[d/l]

      If really all you want is that one item and it is on one line of your XML file, use a regex: /^\s*<info name="now_playing">(.*?)<\/info>$/

      If you're going to use a regex don't bother with anchors or or backslashes :) 

      my( $fo ) = m{
\Q<info name="now_playing">\E
(.*?)
\Q</info>\E  }sx;

      [download]
[reply]
[d/l]

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