samdeepthink

May 14, 2026 · Backend Development

Designing a Group Order Module: Unified Payment and Post‑Payment Cost Splitting

This article details a production‑grade group‑order system where a single initiator pays the total order, then uses WeChat's group‑collection API to split costs among participants, covering the full workflow, data model, Redis caching strategy, payment callbacks, cost‑allocation formulas, state machine, and operational constraints.