E-commerce API — Django REST, Redis Cart, Stripe Payments

Production-minded E-commerce REST API built with Django and Django REST Framework (DRF), featuring JWT authentication, a Redis-backed cart, order processing with a robust state machine, and Stripe PaymentIntent integration.

Designed to demonstrate real backend engineering concerns: async work offloading, data integrity, concurrency safety, and reliable webhook ingestion.

---

Key Features

• JWT Authentication (SimpleJWT): register/login/logout, profile, password change, password reset
• Product & Category management with pagination and filtering
• Redis-backed cart (fast reads/writes, expiration, stock checks)
• Order processing from cart → order items + stock decrement
• Robust order state machine preventing invalid transitions (e.g., canceled → paid)
• Stripe integration: create PaymentIntent + webhook updates for payments
• Async processing with Celery + Redis for non-blocking tasks (email + webhook processing; extensible to invoice/PDF generation)
• Concurrency control: database row-level locking using select_for_update() during critical sections

---

Quickstart (Local Development)

Prerequisites

• Python 3.10+
• Redis (used for cart storage and Celery broker/result backend)
• Stripe account (for PaymentIntents + webhook signature verification)

1) Create and activate a virtual environment

python -m venv .venv
source .venv/bin/activate

2) Install dependencies

pip install -r requirements.txt

3) Configure environment variables

Create a .env file at the project root:

# Django
SECRET_KEY=change-me

# Email (used by password reset task)
EMAIL_USER=your_email@example.com
EMAIL_PASS=your_email_password
FROM_EMAIL=your_email@example.com

# Stripe
STRIPE_PUBLISHABLE_KEY=pk_test_...
STRIPE_SECRET_KEY=sk_test_...
STRIPE_WEBHOOK_SECRET=whsec_...

# Celery (optional overrides)
CELERY_BROKER_URL=redis://127.0.0.1:6379/0
CELERY_RESULT_BACKEND=redis://127.0.0.1:6379/3

4) Run migrations

python manage.py migrate

5) Create an admin user (optional)

python manage.py createsuperuser

6) Start Redis

If you already have Redis installed locally:

redis-server

By default, this project uses separate Redis logical databases:

• redis://127.0.0.1:6379/2 for cache/cart
• redis://127.0.0.1:6379/0 for the Celery broker
• redis://127.0.0.1:6379/3 for the Celery result backend

Or via Docker:

docker run --rm -p 6379:6379 redis:7-alpine

7) Start Celery worker

In a separate terminal:

celery -A ecommerce worker -l info

8) Run the Django development server

python manage.py runserver

---

Stripe Webhooks (Local)

This project validates webhook signatures using STRIPE_WEBHOOK_SECRET and queues processing to Celery.

Recommended local workflow using the Stripe CLI:

stripe listen --forward-to http://127.0.0.1:8000/api/v1/payments/webhook/

Then copy the printed webhook secret (whsec_...) into your .env.

---

API Endpoints (Current Routes)

Base URL prefix: /api/v1/

Auth & Users

• POST /api/v1/users/register/
• POST /api/v1/users/login/
• POST /api/v1/users/logout/
• GET /api/v1/users/me/
• PUT /api/v1/users/me/update/
• POST /api/v1/users/change-password/
• POST /api/v1/users/send-reset-password-email/
• POST /api/v1/users/reset-password/<uid>/<token>/
• GET /api/v1/users/ (admin)
• GET /api/v1/users/<id>/ (admin)

Products & Categories

• GET/POST /api/v1/products/
• GET/PUT/DELETE /api/v1/products/<id>/
• GET/POST /api/v1/categories/
• GET/PUT/DELETE /api/v1/categories/<id>/

Cart (Redis-backed)

• GET /api/v1/cart/
• DELETE /api/v1/cart/ (clear cart)
• POST /api/v1/cart/items/ (add item)
• PUT /api/v1/cart/items/<product_id>/ (update quantity)
• DELETE /api/v1/cart/items/<product_id>/ (remove)

Orders

• GET/POST /api/v1/orders/
• GET /api/v1/orders/<id>/
• PUT /api/v1/orders/<id>/status/ (admin)
• PUT /api/v1/orders/<id>/cancel/

Payments (Stripe)

• POST /api/v1/payments/create-payment-intent/
• POST /api/v1/payments/webhook/ (Stripe)

---

Authentication (JWT)

After login/register, include the access token:

Authorization: Bearer <access_token>

---

API Documentation (Swagger / Redoc)

OpenAPI schema and interactive documentation are available via drf-spectacular:

• OpenAPI schema: /api/schema/
• Swagger UI: /api/docs/swagger/
• Redoc: /api/docs/redoc/

---

Design Patterns Used

• Service Layer: business logic encapsulation (e.g., Redis cart operations in a dedicated service)
• State Machine: order status transitions are centrally enforced on the model
• Async Workers: Celery tasks for background work (email + Stripe webhook processing)

---

Running Tests

python manage.py test

---

Future Improvements

• PostgreSQL migration for production-grade transactions/locking and better scalability
• Dockerization (Django + Redis + Celery) for reproducible local/prod environments
• CI/CD pipeline (linting, unit tests, build, deploy)
• Idempotency for webhooks (store processed event IDs) for extra safety under retries

---

Tech Stack

• Django, Django REST Framework
• Celery + Redis
• SQLite (development)
• Stripe API