Payment

0 articles

Order Payment Pipeline: Coupon + Flash Sale + Coins + Group Buy Four-Layer Price Calculation

An in-depth analysis of the `OrderService.checkOut` method in a NestJS project, demonstrating how to chain four layers of price calculation (flash sale, coupon, coins, group buy) and five subsystems within a Prisma transaction, covering optimistic lock debit, atomic inventory deduction, and a complete refund flow.

Backend Development

Avatar Service, Payment Integration, and Public Cache Interceptor

JoyMini API's automatic avatar generation service (Sharp compositing + BullMQ queue), Xendit payment integration (with distributed lock reconciliation), and a Redis-based public cache interceptor implementation.

Interface Management

Deep Dive into Payment Webhook & Callback Handling — Optimistic Locking, Idempotency, Atomic Wallet Operations

In-depth analysis of PaymentWebhookController (single endpoint routing + callback-token authentication) → handleUniversalWebhook (deposit/withdrawal routing) → handleInvoiceWebhook (updateMany optimistic locking + creditCash) → handlePayoutWebhook (atomic unfreeze + CRITICAL degradation) → WalletService (ensureWallet / creditCash / freezeCash / unfreezeCash + beforeBalance/afterBalance audit trail)

Management Backend

Full Payment Process Chain — API Xendit → Flutter App → admin-next Financial Audit

NestJS PaymentService (Xendit Invoice/Payout Gateway) → ClientWalletService (Deposit/Withdrawal/Webhook Callback Business Logic) → admin-next Finance Page (WithdrawalList, DepositList, TransactionList)

Management Backend