public function hasAtLeast($field, $count, $message = null, $when = null)
    {
        $extra = array_filter(['on' => $when, 'message' => $message]);

        return $this->add($field, 'hasAtLeast', $extra + [
            'rule' => function ($value) use ($count) {
                if (is_array($value) && isset($value['_ids'])) {
                    $value = $value['_ids'];
                }

                return Validation::numElements($value, Validation::COMPARE_GREATER_OR_EQUAL, $count);
            }
        ]);
    }