use Data::FormValidator;
use Data::FormValidator::Constraints::DateTime qw(to_datetime);
use CGI;

use My::Customer;

my $results = Data::FormValidator->check(
    CGI->new,
    {
        constraints => {
            customer => My::Customer->constraint,
            date     => to_datetime('%D'),
        }
    }
);

if( $results->success )
{
    my $date     = $results->valid('date');
    my $customer = $results->valid('customer');

    $date->year;
    $customer->address->zipcode;
}

##</code><code>##

package My::Customer;
use base 'My::Class::DBI';

sub constraint
{
    my $pkg = shift;
    return sub {
        my $value = shift;
        return unless $value =~ /^(\d+)$/;
        return $pkg->retrieve($value);
    };
}