public static function find_ongoing_request_types_for_users(array $userids) : array {
        global $DB;

        if (empty($userids)) {
            return [];
        }

        // Check if the user already has an incomplete data request of the same type.
        $nonpendingstatuses = [
            self::DATAREQUEST_STATUS_COMPLETE,
            self::DATAREQUEST_STATUS_CANCELLED,
            self::DATAREQUEST_STATUS_REJECTED,
            self::DATAREQUEST_STATUS_DOWNLOAD_READY,
            self::DATAREQUEST_STATUS_EXPIRED,
            self::DATAREQUEST_STATUS_DELETED,
        ];
        list($statusinsql, $statusparams) = $DB->get_in_or_equal($nonpendingstatuses, SQL_PARAMS_NAMED, 'st', false);
        list($userinsql, $userparams) = $DB->get_in_or_equal($userids, SQL_PARAMS_NAMED, 'us');

        $select = "userid {$userinsql} AND status {$statusinsql}";
        $params = array_merge($statusparams, $userparams);

        $requests = $DB->get_records_select(data_request::TABLE, $select, $params, 'userid', 'id, userid, type');

        $returnval = [];
        foreach ($userids as $userid) {
            $returnval[$userid] = (object) [];
        }

        foreach ($requests as $request) {
            $returnval[$request->userid]->{$request->type} = true;
        }

        return $returnval;
    }