I find XML::Simple to be very simple if the XML is very simple, but with non-trivial XML I am often surprised by what it produces and, if I persist with it, end up spending a lot of time re-reading the documentation and studying Data::Dumper dumps.

Here is an example which shows, step by step as I worked it out, how to access the source_name element...

use strict;
use warnings;
use Data::Dumper;

my $VAR1 = {
    'sas_residue_annotation' => [
        {
            'xmlns'   => 'http://www.ebi.ac.uk/WSsas/Schema',
            'sources' => [
                {
                    'source' => [
                        {
                            'source_name'  => [ '1iho' ],
                            'ref_evalue'   => [ '5.5e-50' ],
                            'ref_overlap'  => [ '282' ],
                            'ref_identity' => [ '47.20' ],
                            'ref_pmid'     => [ '11377204' ]
                        },
                        {
                            'source_name'  => [ '1mop' ],
                            'ref_evalue'   => [ '8.3e-38' ],
                            'ref_overlap'  => [ '264' ],
                            'ref_identity' => [ '43.60' ],
                            'ref_pmid'     => [ '12717031' ]
                        },
                        {
                            'source_name'  => [ '1n2b' ],
                            'ref_evalue'   => [ '8.2e-38' ],
                            'ref_overlap'  => [ '264' ],
                            'ref_identity' => [ '43.60' ],
                            'ref_pmid'     => [ '12717031' ]
                        },
                    ],
                },
            ],
        },
    ],
};

print Dumper($VAR1);
print Dumper($VAR1->{sas_residue_annotation});
print Dumper($VAR1->{sas_residue_annotation}[0]);
print Dumper($VAR1->{sas_residue_annotation}[0]{sources});
print Dumper($VAR1->{sas_residue_annotation}[0]{sources}[0]);
print Dumper($VAR1->{sas_residue_annotation}[0]{sources}[0]{source});

foreach my $source (@{$VAR1->{sas_residue_annotation}[0]{sources}[0]{s
+ource}}) {
    print "source name: ", join(',',@{$source->{source_name}}), "\n";
}

[download]

Note that I wrote each successive print after studying the output of the previous one. It is a bit tedious, but for deeply nested structures I find it faster than trying to do it all in my head and then debugging my errors.

In reply to Re^3: request for help on working with XML::Simple by ig
in thread request for help on working with XML::Simple by Angharad

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.