isUnique Validator for Lithium (li3) PHP Framework

validatorIsUnique.php

Validator::add('isUnique', function($data, $params, $options) {
	$model = $options['model'];
	$field = $options['field'];
	$key = $model::meta('key');

	$entity = $model::first(array('conditions' => array($field => $data)));

	$identifier =  isset($options['values'][$key]) ? $options['values'][$key] : null;

	if ($entity && $entity->data() && $identifier == (string) $entity->$key) {
		return false;
	}
	return true;
});