history - serialize()

ApiController.php

$history[Carbon::now()->toDateTimeString()] = [
                "title" => "무통장입금 저장",
                "application_no" => $application_no,
                "discount_id" => $discount_id,
                "discount_code" => $discount_code,
                "premium_expect" => $premium_expect,
                "account_id" => $account_id,
                "account_name" => $account_name,
            ];