wintermute_115 has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to parse RSS feeds with XML::RSS::Parser, and it's mostly working fine, except that I need to be able to pull the content of elements in the itunes namespace and nothing I can think of seems to work.

If I'm trying to read the element itunes:summary (it will be en object of type XML::RSS::Parser::Element), for example, I've tried: 

$summary = $element->query('itunes:summary');
$summary = $element->query('{http://www.itunes.com/dtds/podcast-1.0.dt
+d}summary');
$summary = $element->query('summary')
$summary = $element->query(process_name('itunes:summary'):
$summary = $element->query(process_name('{http://www.itunes.com/dtds/p
+odcast-1.0.dtd}summary'):

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and some other things I don't remember. But everything I try, it ether returns undef or I get told Bad call to match: '<XXX>' contains unknown token.

Does anyone know how this works? Thanks.

Replies are listed 'Best First'.
Re: namespaces in XML::RSS::Parser::Element
by choroba (Cardinal) on Apr 11, 2024 at 23:25 UTC
    Namespace URIs are case sensitive. The namespace your file uses is different to the namespace in the module documentation: 
    file: http://www.itunes.com/dtds/podcast-1.0.dtd
doc:  http://www.itunes.com/DTDs/Podcast-1.0.dtd

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    You can register a new prefix: 

    #!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use XML::RSS::Parser;

my $p = XML::RSS::Parser->new;
$p->register_ns_prefix('lc_itunes',
                       'http://www.itunes.com/dtds/podcast-1.0.dtd');
my $feed = $p->parse_file(*DATA);
for my $item ($feed->query('//item')) {
    say $item->query('lc_itunes:summary')->text_content;
}

__DATA__
<rss xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd"
     xmlns:content="content"
     xmlns="http://purl.org/rss/1.0/"
     xmlns:dc="http://purl.org/dc/elements/1.1/">
     <channel>
         <title>Title</title>
         <link>file:///</link>
         <description/>
         <dc:language>cs_CZ</dc:language>
     </channel>
    <item>
      <guid isPermaLink="false">5460304c-e284-4f84-b4a3-2cccba31fb81</
+guid>
...

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    map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]
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      Thank you! I don't think I'd ever have noticed that without the pointer.
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Re: namespaces in XML::RSS::Parser::Element
by choroba (Cardinal) on Apr 11, 2024 at 16:05 UTC
    Can you also paste an example of the RSS you're trying to process?

    Update: Also, what is $element? Even the synopsis shows you should use XPath for queries, maybe you should involve some kind of axis, like //itunes:summary.

    map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]
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      Read more... Example RSS item (5 kB)

      $element is being generated by foreach my $element ($rss->query('//item')) to grab individual items from within the RSS feed.

      I've never worked with XPath before, but based on the Wikipedia page it looks like my $summary = $element->query('//itunes:summary'); ought to work, but it's still returning undef.

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