retail-nest/SETUP_COMPLETE.md

🎉 NestJS Retail POS Backend - Setup Complete!

Your complete NestJS backend API for the Retail POS Flutter application has been successfully created!

---

📦 What's Been Created

✅ Core Infrastructure

• NestJS Application: Latest version with TypeScript
• PostgreSQL Database: Complete schema with migrations
• Redis Caching: Ready for performance optimization
• JWT Authentication: Secure token-based auth
• Role-Based Access Control (RBAC): Admin, Manager, Cashier, User roles
• Swagger Documentation: Auto-generated API docs

✅ Database Layer

• 5 Entities: User, Category, Product, Transaction, TransactionItem
• Initial Migration: Complete schema with 11 indexes
• Seed Data: Sample categories, products, and users
• TypeORM Configuration: Production-ready setup

✅ API Modules

1. Auth Module (/api/auth)

• POST /auth/register - Register new user
• POST /auth/login - Login with JWT
• GET /auth/profile - Get current user
• POST /auth/refresh - Refresh token

2. Users Module (/api/users)

• Complete CRUD for user management
• Admin-only access
• Password hashing with bcrypt

3. Categories Module (/api/categories)

• GET /categories - List all categories (Public)
• GET /categories/:id - Get single category (Public)
• GET /categories/:id/products - Products by category (Public)
• POST /categories - Create category (Admin/Manager)
• PUT /categories/:id - Update category (Admin/Manager)
• DELETE /categories/:id - Delete category (Admin only)

4. Products Module (/api/products)

• GET /products - List with pagination, filters, search (Public)
• GET /products/:id - Get single product (Public)
• GET /products/category/:categoryId - By category (Public)
• GET /products/search - Search products (Public)
• POST /products - Create product (Admin/Manager)
• PUT /products/:id - Update product (Admin/Manager)
• DELETE /products/:id - Delete product (Admin only)

5. Transactions Module (/api/transactions)

• GET /transactions - List transactions (Cashier+)
• GET /transactions/:id - Get transaction (Cashier+)
• POST /transactions - Create transaction (Cashier+)
• GET /transactions/stats - Statistics (Manager+)
• GET /transactions/stats/daily - Daily sales (Manager+)

Features:

• ✅ Atomic transaction processing
• ✅ Stock validation and updates
• ✅ Automatic tax calculation (10%)
• ✅ Price snapshots at transaction time
• ✅ Pessimistic locking for concurrency

6. Sync Module (/api/sync)

• POST /sync - Sync all data (Cashier+)
• POST /sync/products - Sync products only (Cashier+)
• POST /sync/categories - Sync categories only (Cashier+)
• GET /sync/status - Get sync status (Cashier+)

Features:

• ✅ Incremental sync based on timestamps
• ✅ Offline-first mobile support
• ✅ Efficient bandwidth usage

✅ Common Utilities

• DTOs: Pagination, API Response wrappers
• Filters: HTTP exception handler, catch-all filter
• Interceptors: Logging, response transformation, caching
• Pipes: Global validation pipe
• Guards: JWT auth guard, roles guard
• Decorators: @CurrentUser(), @Public(), @Roles()

✅ Configuration

• Environment Variables: .env file with dummy data
• TypeScript Config: Strict mode enabled
• ESLint & Prettier: Code formatting
• Jest: Testing framework setup

✅ Docker Setup

• Dockerfile: Multi-stage build for production
• docker-compose.yml: Complete stack (API, PostgreSQL, Redis, pgAdmin)
• .dockerignore: Optimized build context

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🚀 Quick Start

Option 1: Local Development

1. Create Database

# Using psql
createdb retail_pos

# Or using Docker
docker-compose up -d postgres redis

2. Configure Environment

The .env file is already created with dummy data. Update these values:

DB_HOST=localhost
DB_PORT=5432
DB_USERNAME=postgres
DB_PASSWORD=postgres  # Change this!
DB_DATABASE=retail_pos

JWT_SECRET=retail-pos-super-secret-key-change-in-production-2025  # Change this!

3. Run Migrations

npm run migration:run

4. Seed Database (Optional)

npm run seed:run

This creates:

• Categories: 6 retail categories (Electronics, Clothing, Food, etc.)
• Products: 14 sample products
• Users:
  • Admin: admin@retailpos.com / Admin123!
  • Manager: manager@retailpos.com / Manager123!
  • Cashier: cashier@retailpos.com / Cashier123!

5. Start Server

# Development mode with hot-reload
npm run start:dev

# Production mode
npm run build
npm run start:prod

6. Access Application

• API: http://localhost:3000/api
• Swagger Docs: http://localhost:3000/api/docs
• Health Check: http://localhost:3000/health

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Option 2: Docker Deployment

Start All Services

# Start API, PostgreSQL, Redis
docker-compose up -d

# View logs
docker-compose logs -f api

# Include pgAdmin for database management
docker-compose --profile tools up -d

Run Migrations in Docker

docker-compose exec api npm run migration:run
docker-compose exec api npm run seed:run

Access Services

• API: http://localhost:3000/api
• Swagger: http://localhost:3000/api/docs
• pgAdmin: http://localhost:5050 (admin@retailpos.com / admin123)
• PostgreSQL: localhost:5432
• Redis: localhost:6379

---

🔐 Test the API

1. Login to Get Token

curl -X POST http://localhost:3000/api/auth/login \
  -H "Content-Type: application/json" \
  -d '{"email": "admin@retailpos.com", "password": "Admin123!"}'

Response:

{
  "access_token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
  "user": {
    "id": "uuid",
    "email": "admin@retailpos.com",
    "name": "Admin User",
    "roles": ["admin"]
  }
}

2. List Products (Public)

curl http://localhost:3000/api/products

3. Create Product (Auth Required)

curl -X POST http://localhost:3000/api/products \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Gaming Mouse",
    "price": 49.99,
    "categoryId": "CATEGORY_UUID",
    "stockQuantity": 100
  }'

4. Create Transaction

curl -X POST http://localhost:3000/api/transactions \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "items": [
      {"productId": "PRODUCT_UUID", "quantity": 2}
    ],
    "paymentMethod": "cash",
    "discount": 5.00
  }'

---

📚 Project Structure

retail-nest/
├── src/
│   ├── common/                 # Global utilities
│   │   ├── decorators/         # @CurrentUser, @Public, @Roles
│   │   ├── dto/                # PaginationDto, ApiResponseDto
│   │   ├── filters/            # Exception handlers
│   │   ├── guards/             # JWT, Roles guards
│   │   ├── interceptors/       # Logging, Transform, Cache
│   │   └── pipes/              # Validation pipe
│   ├── config/                 # Configuration modules
│   │   ├── app.config.ts
│   │   ├── database.config.ts
│   │   ├── jwt.config.ts
│   │   └── redis.config.ts
│   ├── database/
│   │   ├── migrations/         # TypeORM migrations
│   │   └── seeds/              # Database seeds
│   ├── modules/
│   │   ├── auth/               # Authentication
│   │   ├── users/              # User management
│   │   ├── categories/         # Category API
│   │   ├── products/           # Product API
│   │   ├── transactions/       # Transaction API
│   │   └── sync/               # Mobile sync API
│   ├── app.module.ts
│   └── main.ts
├── test/                       # Unit & E2E tests
├── .env                        # Environment variables
├── .env.example                # Environment template
├── Dockerfile                  # Production Docker image
├── docker-compose.yml          # Full stack setup
└── package.json

---

🎯 Key Features

Security

✅ JWT authentication with refresh tokens ✅ Password hashing with bcrypt (10 rounds) ✅ Role-based access control (RBAC) ✅ Rate limiting (100 req/min) ✅ CORS protection ✅ Helmet security headers

Performance

✅ Redis caching layer ✅ Database query optimization with indexes ✅ Pessimistic locking for transactions ✅ Pagination for large datasets ✅ Response compression (gzip)

Data Integrity

✅ Database transactions for critical operations ✅ Foreign key constraints ✅ Unique constraints ✅ Stock validation before transactions ✅ Price snapshots in transactions

Developer Experience

✅ Swagger/OpenAPI documentation ✅ TypeScript with strict mode ✅ Hot-reload in development ✅ Docker support for easy deployment ✅ Comprehensive error handling

---

🧪 Available Scripts

# Development
npm run start:dev          # Start with hot-reload
npm run start:debug        # Start with debugger

# Production
npm run build              # Build for production
npm run start:prod         # Run production build

# Database
npm run migration:generate # Generate migration
npm run migration:create   # Create empty migration
npm run migration:run      # Run migrations
npm run migration:revert   # Revert last migration
npm run seed:run           # Seed database

# Testing
npm run test               # Run unit tests
npm run test:watch         # Watch mode
npm run test:cov           # With coverage
npm run test:e2e           # E2E tests

# Code Quality
npm run lint               # Lint code
npm run format             # Format with Prettier

---

🔧 Environment Variables

All required environment variables are in .env (already created):

# Application
NODE_ENV=development
PORT=3000
API_PREFIX=api

# Database
DB_HOST=localhost
DB_PORT=5432
DB_USERNAME=postgres
DB_PASSWORD=postgres
DB_DATABASE=retail_pos

# JWT
JWT_SECRET=your-secret-key-here
JWT_EXPIRES_IN=1d

# Redis
REDIS_HOST=localhost
REDIS_PORT=6379
CACHE_TTL=300

# CORS
CORS_ORIGIN=http://localhost:3000,capacitor://localhost

# Rate Limiting
THROTTLE_TTL=60
THROTTLE_LIMIT=100

# Security
BCRYPT_ROUNDS=10

---

📖 API Documentation

Access Swagger UI

Once the server is running, visit:

• Swagger UI: http://localhost:3000/api/docs
• OpenAPI JSON: http://localhost:3000/api/docs-json

Default Users

Role	Email	Password
Admin	admin@retailpos.com	Admin123!
Manager	manager@retailpos.com	Manager123!
Cashier	cashier@retailpos.com	Cashier123!

---

🎨 Response Format

All API responses follow a consistent format:

Success Response

{
  "success": true,
  "data": { /* your data */ },
  "message": "Operation successful"
}

Paginated Response

{
  "success": true,
  "data": [ /* items */ ],
  "meta": {
    "page": 1,
    "limit": 20,
    "total": 100,
    "totalPages": 5
  }
}

Error Response

{
  "success": false,
  "error": {
    "statusCode": 400,
    "message": "Validation failed",
    "details": ["error details"]
  },
  "timestamp": "2025-10-10T12:00:00.000Z",
  "path": "/api/products"
}

---

🚀 Next Steps

1. Update Environment Variables

Edit .env file with your actual database credentials and JWT secret.

2. Run Migrations

npm run migration:run

3. Seed Database

npm run seed:run

4. Start Development Server

npm run start:dev

5. Test API

Visit http://localhost:3000/api/docs to test endpoints.

6. Integrate with Flutter App

• Update Flutter app API base URL to http://localhost:3000/api
• Use JWT token from login response for authenticated requests
• Implement offline sync using /api/sync endpoints

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📝 Additional Documentation

Created documentation files:

• DATABASE_SETUP.md - Complete database guide
• DATABASE_SUMMARY.md - Quick database reference
• AUTH_SYSTEM.md - Authentication system details
• IMPLEMENTATION_SUMMARY.md - Implementation guide

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✨ What Makes This Production-Ready

✅ Security First: JWT auth, bcrypt hashing, RBAC, rate limiting ✅ Scalable Architecture: Modular design, dependency injection ✅ Performance Optimized: Redis caching, database indexes, query optimization ✅ Data Integrity: Transactions, constraints, stock validation ✅ Developer Friendly: Swagger docs, TypeScript, hot-reload ✅ Docker Ready: Multi-stage builds, docker-compose stack ✅ Testing Ready: Jest setup, unit & E2E test structure ✅ Mobile Ready: Sync API for offline-first Flutter app

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🎉 You're All Set!

Your NestJS Retail POS Backend is production-ready and waiting for you to:

1. Update .env with your credentials
2. Run migrations: npm run migration:run
3. Seed data: npm run seed:run
4. Start server: npm run start:dev
5. Open Swagger: http://localhost:3000/api/docs

Happy coding! 🚀