organize validation

[michaelfung]

If there are many endpoints and their parameters are standardized, to avoid repeatition, I plan to organize the validation like this:

# in a plugin, define all validations in a map:
$app->helper(
  'dv_map' => sub ($c) {
    return state $dv_map = {
      email => sub ($v) {
        $v->optional( 'email', 'trim' )->is_email;
      },
      username => sub ($v) {
        $v->required( 'username', 'trim' )->in(qw/mike admin root/);
      },
      password => sub ($v) {
        $v->required( 'password', 'trim' )->like(qr/[[:alnum:]]/)
          ->size( 8, 50 );
      }
 ...

# and in an action:
  my $v = $c->validation;
  for (qw/email username password/) {
    $c->dv_map->{$_}->($v);
  }

Is there any better way to organize this? Thanks!