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Overview

DAF Backend is a robust Express.js-based REST API that powers both Point of Sale (POS) and E-commerce (ECOM) systems. The API implements a unique dual-database architecture with credential-based connection pooling, providing secure and isolated data management for retail and online sales operations.

POS System

Manage in-store operations including inventory, invoices, clients, suppliers, and transactions

E-commerce

Handle online shopping cart, product catalog, payments, and customer authentication

Secure Authentication

JWT-based authentication with database credentials embedded in tokens

PostgreSQL Powered

Two separate PostgreSQL databases with connection pooling and credential-based access

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Key features

The DAF Backend API provides enterprise-grade features for retail and e-commerce management:

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Dual-system architecture

The API operates two independent systems:
  • POS System: Complete retail management with products, raw materials, suppliers, clients, invoices, and inventory tracking
  • E-commerce System: Online shopping functionality with cart management, product browsing, and payment processing

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Secure credential-based connections

Unlike traditional APIs with a single database user, DAF Backend uses a unique approach:
  • Each authenticated user’s database credentials are embedded in their JWT token
  • Database connections are created per-request using the user’s actual credentials
  • This provides database-level security and audit trails

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Rich validation layer

The API uses multiple validation libraries:
  • Zod: Schema validation for e-commerce endpoints
  • Joi: Custom validation for POS endpoints
  • Custom DTOs: Business logic validation for complex entities

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File upload support

Product images are handled through:
  • Multer middleware for multipart form data
  • Disk storage with unique filename generation
  • Image serving through Express static middleware

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Technology stack

The DAF Backend is built with modern, production-ready technologies: 
{
  "name": "daf-backend",
  "version": "1.0.0",
  "dependencies": {
    "express": "^5.2.1",
    "pg": "^8.17.1",
    "jsonwebtoken": "^9.0.3",
    "cors": "^2.8.5",
    "dotenv": "^17.2.3",
    "multer": "^2.0.2",
    "sharp": "^0.34.5",
    "joi": "^18.0.2",
    "zod": "^4.3.5"
  }
}

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Core technologies

  • Express.js 5.2: Modern Node.js web framework
  • PostgreSQL: Enterprise-grade relational database
  • pg (node-postgres): Connection pooling and query execution
  • JWT: Secure token-based authentication
  • Multer: Multipart form data and file uploads
  • Zod & Joi: Schema validation libraries

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Who should use this documentation

This documentation is designed for:
1

Backend Developers

Developers integrating with the DAF Backend API or extending its functionality
2

Frontend Teams

Teams building POS or e-commerce interfaces that consume these endpoints
3

System Administrators

Admins deploying and maintaining the DAF Backend infrastructure
4

Database Engineers

Engineers managing PostgreSQL databases and understanding the credential-based connection model

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API structure

The API is organized into two main namespaces:

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POS endpoints

All POS endpoints are prefixed with /api/pos/:
  • /api/pos/auth - Authentication and access control
  • /api/pos/cliente - Client management
  • /api/pos/producto - Product catalog
  • /api/pos/factura - Invoice generation
  • /api/pos/proveedor - Supplier management
  • /api/pos/materiaprima - Raw materials inventory
  • /api/pos/kardex* - Inventory movement tracking
  • /api/pos/ordencompra - Purchase orders

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E-commerce endpoints

All e-commerce endpoints are prefixed with /api/ecom/:
  • /api/ecom/auth - User registration and login
  • /api/ecom/producto - Product browsing
  • /api/ecom/carrito - Shopping cart operations
  • /api/ecom/pagos - Payment processing
  • /api/ecom/ciudad - City/location data
Both systems use JWT authentication, but with different token structures and database connections.

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Next steps

Quickstart

Get the API running locally in minutes

Authentication

Learn how JWT authentication works in DAF Backend

Architecture

Understand the dual-system architecture

Database

Explore database configuration and connection pooling

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