🚀 @gotocva/nestjs-utils

A reusable utility library for NestJS applications. This package includes cryptographic helpers, JWT handling, global exception filtering, response interceptors, and more.

📦 Features

• 🔐 AES-256-CBC encryption/decryption
• 🔑 JWT token generation, verification, and decoding
• ⚠️ Global exception handler with MongoDB error awareness
• 📦 Standardized API response formatting
• 🧾 SHA-256 hashing utilities

📦 Installation

npm install @gotocva/nestjs-utils

Or via GitHub:

npm install git+https://github.com/your-org/nestjs-utils.git

Ensure you have @nestjs/jwt and @nestjs/common installed.

🔧 Usage

1. Crypto Utilities

import { createTransactionHash, createContractAddress, encrypt, decrypt } from '@gotocva/nestjs-utils';

// Hashing
const txHash = createTransactionHash({ sender: 'alice', amount: 100 });
const contractAddr = createContractAddress('SomeContractIdentifier');

// Encryption/Decryption
const key = crypto.randomBytes(32); // Or load from config
const encrypted = encrypt('my-secret-data', key);
const decrypted = decrypt(encrypted, key);

2. JWT Handler

import { JwtHandler } from '@gotocva/nestjs-utils';
import { JwtService } from '@nestjs/jwt';

const jwtHandler = new JwtHandler(new JwtService({ secret: process.env.JWT_SECRET }));

const token = jwtHandler.generateToken({ userId: 123 });
const verified = jwtHandler.verifyToken(token);
const decoded = jwtHandler.decodeToken(token);

3. Global Exception Filter

import { ExceptionHandler } from '@gotocva/nestjs-utils';
import { APP_FILTER } from '@nestjs/core';

@Module({
  providers: [
    {
      provide: APP_FILTER,
      useClass: ExceptionHandler,
    },
  ],
})
export class AppModule {}

Handles:

• Mongoose validation errors
• MongoDB error codes (duplicate key, validation, unauthorized, etc.)
• Custom HttpException

4. Response Interceptor

import { ResponseInterceptor } from '@gotocva/nestjs-utils';
import { APP_INTERCEPTOR } from '@nestjs/core';

@Module({
  providers: [
    {
      provide: APP_INTERCEPTOR,
      useClass: ResponseInterceptor,
    },
  ],
})
export class AppModule {}

All HTTP responses will follow a consistent format:

{
  "message": "Success message",
  "status": true,
  "result": { /* your data */ },
  "error": null,
  "timestamps": "2025-05-11T00:00:00.000Z",
  "status_code": 200,
  "path": "/api/example"
}

🛠 Configuration

• Set JWT_SECRET in your environment variables for the JwtHandler.
• AES encryption keys must be 32 bytes for aes-256-cbc.

🧪 Testing

To test the utility functions independently:

npm run test

Add test coverage for each utility as needed.

🧑‍💻 Contributing

1. Fork the repository
2. Create your feature branch: git checkout -b feature/my-utils
3. Commit your changes
4. Push to the branch
5. Open a Pull Request

📄 License

MIT License © Sivabharathy