Dev builds e-commerce backend with atomic order transactions using Prisma and PostgreSQL

A developer completing a CodeAlpha Full Stack internship built an e-commerce backend as the second of two projects, using Express, Prisma, PostgreSQL, and JWT. The system covers products, cart management, and order placement, with the core focus on ensuring orders are created atomically — meaning stock updates and cart clearing happen together or not at all. A key schema decision was storing a price snapshot on each OrderItem rather than referencing the live product price, so historical orders always reflect what the customer actually paid. Cart integrity is enforced via a compound unique constraint on user and product, allowing Prisma's upsert to prevent duplicate cart rows at the database level. Admin roles are assigned manually rather than through a self-service flow, a deliberate security choice, with the user role embedded directly in the JWT payload for route-level authorization.