Here's a general routine that will tell you if a particular branch of a hash exists. In otherwords, if you have this:

    $hash{ foo }{ bar }{ baz }
[download]

It can be a pain to check for the existence of every single key.

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

my %hash = (
    one => {
        test => 3
    },
    two => {
        Ovid => {
            is => {
                a => 'fool'
            }
        }
    }
);

if ( hash_branch_exists( \%hash, qw/ one test / ) ) {
    print "Good\n";
} else {
    print "Bad\n";
}

if ( hash_branch_exists( \%hash, qw/ Ovid is a fool / ) ) {
    print "Good\n";
} else {
    print "Bad\n";
}

if ( hash_branch_exists( \%hash, qw/ two Ovid Is a / ) ) {
    print "Good\n";
} else {
    print "Bad\n";
}

sub hash_branch_exists {
    my ( $hash_ref, @fields ) = @_;

    foreach ( @fields ) {
        return 0 if ref $hash_ref ne 'HASH';
        return 0 if ! exists $hash_ref->{ $_ };
        $hash_ref = $hash_ref->{ $_ };
    }
    return 1;
}
[download]

Cheers,
Ovid

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