use Data::FormValidator;
use CGI;
my $q = CGI->new;
my %profile = (
    required => [qw( io )],
    constraints => {
        io => 'RE_num_int' # use a Regexp::Common test
    },
    untaint_all_constraints => 1,
);
my $results = Data::FormValidator->check($q, \%profile);

if ($results->has_invalid or $results->has_missing) {
    # do something with $results->invalid, $results->missing
    # or  $results->msgs
}
else {
    # do something with $results->valid
}