Reading and Formatting RSS Feed

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

I have and iPod, and I'm trying to write a program that will read RSS feeds, format them, and save them onto my iPod. I have no problem saving them to the iPod, but here's what I need help with: I've tried using XML::RSS::Parser in a program like this:

        #!/usr/bin/perl -w
    
    use strict;
    use XML::RSS::Parser;
    use URI;
    use LWP::UserAgent;
    use Data::Dumper;
    
    my $ua = LWP::UserAgent->new;
    $ua->agent('XML::RSS::Parser Test Script');
    my @places=( 'http://www.mplode.com/tima/xml/index.xml' );
    
    my $p = new XML::RSS::Parser;
    
    foreach my $place ( @places ) {
    
        # retreive feed
        my $url=URI->new($place);
        my $req=HTTP::Request->new;
        $req->method('GET');
        $req->uri($url);
        my $feed = $ua->request($req);
    
        # parse feed
        $p->parse( $feed->content );
    
        # print feed title and items data dump to screen
        print $p->channel->{ $p->ns_qualify('title', $p->rss_namespace
+_uri ) }."\n";
        my $d = Data::Dumper->new([ $p->items ]);
        print $d->Dump."\n\n";
    
    }
[download]

The above is the program listed in the documentation of XML::RSS::Parser. The program works fine, but I do not know how to use $p->items. In the documentation of XML::RSS::Parser, it says $p->items returns a reference to an array of hash references. How do you work with a refrence to an array of hash refrences? Refrences have always confused me, and I don't think the Camel explains it in simple enough terms. Thanks in advance,

-munchie

Comment on Reading and Formatting RSS Feed Download Code

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Re: Reading and Formatting RSS Feed by pzbagel (Chaplain) on Jul 02, 2003 at 16:02 UTC
That's a perfect reason to pick up Randal's new book: Learning Perl Objects, References & Modules. There is also perldoc perlref and perldoc perlreftut. If you are ever in doubt of what your memory structure looks like, use Data::Dumper to print it out! Here is a quick example of dereferencing an array of hashes. #!/usr/bin/perl -w use strict; # Data::Dumper so we can dump out datastructure later use Data::Dumper; # Let's create an anonymous array with two elements, each a reference + to an anonymous hash. my $aref=[ {a => '1', b => '2'}, {c => '3', d => '4'} ]; #Now dump each element of the array print Dumper($aref->[0]); print Dumper($aref->[1]); #Now dereference single elements, the arrow '->' tells perl to derefen +ce $aref, the you can select elements from the hash using the normal +{} syntax print "c is $aref->[1]{c}\n"; print "a is $aref->[0]{a}\n"; ## Ouput ############### $VAR1 = { 'a' => '1', 'b' => '2' }; $VAR1 = { 'c' => '3', 'd' => '4' }; c is 3 a is 1 [download] HTH	[reply] [d/l]
Re: Reading and Formatting RSS Feed by davorg (Chancellor) on Jul 02, 2003 at 15:53 UTC
`# $p->items is a reference to an array # therefore @{$p->items} is an array. foreach (@{$p->items}) { # Now $_ is a reference to a hash. # You can get to the whole hash like this my @keys = keys %{$_}; # or access individual elements like this my $value = $_->{$keys[0]}; }` [download] -- <http://www.dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l]
Re: Reading and Formatting RSS Feed by sauoq (Abbot) on Jul 02, 2003 at 15:51 UTC
How do you work with a refrence to an array of hash refrences? `my $ref = [ { foo => 'bar' }, { baz => 'qux' } ]; print $ref->[0]{foo}, "\n"; print $ref->[1]{baz}, "\n";` [download] BTW, It's r-e-f-e-r-e-n-c-e with 4 'e's. -sauoq "My two cents aren't worth a dime.";	[reply] [d/l]
Re: Reading and Formatting RSS Feed by gellyfish (Monsignor) on Jul 03, 2003 at 11:04 UTC
As a complete aside and nothing to do with your real question, if all you need to do is re-format the RSS have you considered using XSLT to do this ? XSLT is supported in Perl by XML::LibXSLT ( or if you really need to XML::XSLT ;-) One advantage of going this route is that you can have a single program to format the data in several different ways and all you need to change is the stylesheet. /J\	[reply]
Re: Reading and Formatting RSS Feed by munchie (Monk) on Jul 02, 2003 at 15:51 UTC
This is odd... I was logged in when I posted this, but it says by "Anonymous Monk" -munchie	[reply]