@arbio/common

Shared package for cross-service models, types, validation, middlewares, and errors.
Used by all services (e.g., auth, todos) to ensure consistency and avoid duplication.

Contents

🗂 Entities

Located in src/entities/:

• User entity

• Todo entity

These are TypeORM entities used across services to interact with the database.

📝 DTOs & Validation

Located in src/dto/:

• UserDTO — Data transfer object for user-related API input/output.

• TodoDTO — Data transfer object for todo-related API input/output.

DTOs are separated from DB entities to allow for proper validation and API transport types.

🚦 Middlewares

Located in src/middlewares/. Here are some examples:

• requireAuth — Middleware that ensures the user is authenticated (requires a valid JWT or session).

• validateRequest — Middleware that validates incoming requests using express-validator and throws a standardized error if validation fails.

🛠 Errors

Located in src/errors/:

• BadRequestError — To indicate invalid client input (HTTP 400).

• NotFoundError — To indicate a resource was not found (HTTP 404).

• UnauthorizedError — To indicate authentication failure (HTTP 401).

• CustomError — Base error class to standardize error handling across services.

🚀 Usage

Install

npm install @arbio/common

Import in Services

Entities

import { User } from '@arbio/common';
import { Todo } from '@arbio/common';

DTOs

import { UserDTO } from '@arbio/common';
import { TodoDTO } from '@arbio/common';

Middlewares

import { requireAuth, validateRequest } from '@arbio/common';

Errors

import { BadRequestError, NotFoundError, UnauthorizedError } from '@arbio/common';

🛠 Development

Build

npm run build

📦 Publishing

1. Make your changes.

2. Bump the version:

npm version patch

3. Build the package:

npm run build

4. Publish to npm:

npm publish

✨ Notes

• When adding new things, make sure you export them via src/index.ts.

• Follow semantic versioning when publishing new versions to avoid breaking dependent services.