Common Library

This package contains shared code and utilities used across the MyMTN-Backend microservices architecture.

Installation

npm install @my-oneapp/common

Features

Error Handling

Located in /src/errors:

• BadRequestError - For invalid request handling
• CustomError - Base error class for consistent error formatting
• DatabaseConnectionError - Database connectivity issues
• NotAuthorizedError - Authentication/Authorization failures
• NotFoundError - Resource not found errors
• RequestValidationError - Request validation failures

Constants

Located in /src/constants:

• config.ts - Shared configuration constants
• roles.ts - User role definitions
• statuses.ts - Common status codes and messages

Middleware

Located in /src/middlewares:

• current-user.ts - Extracts and validates current user from JWT
• error-handler.ts - Global error handling middleware
• require-auth.ts - Authentication middleware
• validate-request.ts - Request validation middleware

Events

Located in /src/events:

• subjects.ts - Event subjects for message broker communication

Utils

Located in /src/utils:

• jwt.ts - JWT token management (signing, verification)
• logger.ts - Centralized logging utility
• response.ts - Standardized API response formatting

Usage Examples

Error Handling

import { NotFoundError } from "@my-oneapp/common";

if (!user) {
  throw new NotFoundError("User not found");
}

Authentication

import { requireAuth } from "@my-oneapp/common";

router.post("/api/resource", requireAuth, (req, res) => {
  // Only authenticated users can access this route
});

JWT Operations

import { JWT } from "@my-oneapp/common";

// Sign a new token
const token = JWT.sign({
  id: user.id,
  email: user.email,
  role: user.role,
});

// Verify a token
const payload = JWT.verify(token);

Response Formatting

import { Response } from "@my-oneapp/common";

res.json(Response.success("Operation successful", data));
res.json(Response.error("Operation failed", error));

Environment Variables

The library requires the following environment variables:

• JWT_SECRET - Secret key for JWT operations
• NODE_ENV - Environment name ('development', 'production', 'test')

Contributing

1. Create a feature branch from main
2. Make your changes
3. Update tests if necessary
4. Submit a pull request

Testing

npm run test

Building

npm run build

The build output will be in the /build directory.

License

Internal use only - MyMTN Backend Services