GUMP::validate_valid_json_string PHP Method

    protected function validate_valid_json_string($field, $input, $param = null)
    {
        if (!isset($input[$field]) || empty($input[$field])) {
            return;
        }
        if (!is_string($input[$field]) || !is_object(json_decode($input[$field]))) {
            return array('field' => $field, 'value' => $input[$field], 'rule' => __FUNCTION__, 'param' => $param);
        }
    }