How to validate select box input in Laravel4

Question

Currently when I want to validate a select box I need to include all the values within the validation field.

public static $rules = array(
    'type' => array('required', 'in:a,b,c,d')
);

Is there a best practise way to do this using an array?

For example: I have a long list of country names and want to include this as the validation list. The hacky way of doing this would be something along the lines of:

public static $rules = array(
    'type' => array('required', 'in:'.implode(',', $countries))
);

Thanks

Answer 1

A custom is possible, but a exist-rule can also do the job. More details on http://laravel.com/docs/validation#rule-exists