msh-error

Micro-service helper: node error

This project is intended to be used in typescript project.

• Install
• Documentation
• Usage
  • With custom message
  • Pass some payload
  • Error HOF (higher-order function)
  • Express middleware
  • ErrorBaseModel
  • HttpResponseCodeMapper
• Migration

Install

npm i @beecode/msh-error

Documentation

Usage

import { errorFactory } from '@beecode/msh-error'

export const testService = {
	someFunction: () => {
		// ...
		if(isThereAnError) {
			throw errorFactory().client.forbidden();
			// FORBIDDEN: 403 - FORBIDDEN
			//     at Object.closure ...
			// 	   at file:...
			// 	   at ModuleJob.run (node:...) {
			//   httpCode: 403,
			// 	 payload: undefined
			// }
		}
		// ...
	}
}

With custom message

import { errorFactory } from '@beecode/msh-error'

export const testService = {
	someFunction: () => {
		// ...
		if(isThereAnError) {
			throw errorFactory().client.forbidden('Some custom message')
			// FORBIDDEN: Some custom message
			//     at Object.closure ...
			// 	   at file:...
			// 	   at ModuleJob.run (node:...) {
			//   httpCode: 403,
			//   payload: undefined
			// }
		}
		// ...
	}
}

Pass some payload

import { errorFactory } from '@beecode/msh-error'

export const testService = {
	someFunction: () => {
		// ...
		if(isThereAnError) {
			throw errorFactory().client.forbidden({ message:"Some custom message", payload: { some:"custom", data:"here" } })
			// FORBIDDEN: Some custom message
			//     at Object.closure ...
			// 	   at file:...
			// 	   at ModuleJob.run (node:...) {
			//   httpCode: 403,
			// 	 payload: { some: 'custom', data: 'here' }
			// }
		}
		// ...
	}
}

Error HOF (higher-order function)

errorHOF is the lower-level building block behind errorFactory. It takes an HttpResponseCodeMapper enum value and returns a closure that creates ErrorBaseModel instances. Use it when you need an error for a status code not covered by the factory's predefined methods.

import { errorHOF, HttpResponseCodeMapper } from '@beecode/msh-error'

const serviceUnavailable = errorHOF(HttpResponseCodeMapper.SERVICE_UNAVAILABLE)

// With a custom message
throw serviceUnavailable('Service is down for maintenance')

// With message and payload
throw serviceUnavailable('Service is down', { retryAfter: 60 })

Express middleware

expressMiddleware is a ready-made Express error-handling middleware. It catches thrown ErrorBaseModel instances and responds with the appropriate HTTP status code and a JSON body. Unknown errors fall back to 500.

import express from 'express'
import { expressMiddleware, errorFactory } from '@beecode/msh-error'

const app = express()

// ... your routes ...

// Register as the last middleware (4 arguments = error handler)
app.use(expressMiddleware)

// Example: a route that throws
app.get('/protected', (_req, _res) => {
	throw errorFactory().client.unauthorized()
	// Responds with: { "code": 401, "message": "UNAUTHORIZED: 401 - UNAUTHORIZED", "status": "error" }
})

ErrorBaseModel

ErrorBaseModel is the base error class that all errors from this package extend. It extends the native Error and adds httpCode and payload properties. You can use instanceof to identify these errors in catch blocks.

import { ErrorBaseModel } from '@beecode/msh-error'

try {
	// some code that throws
} catch (err) {
	if (err instanceof ErrorBaseModel) {
		console.log(err.httpCode) // e.g. 403
		console.log(err.payload)  // e.g. { some: 'data' }
	}
}

You can also construct one directly:

import { ErrorBaseModel, HttpResponseCodeMapper } from '@beecode/msh-error'

const error = new ErrorBaseModel({
	httpCode: HttpResponseCodeMapper.BAD_REQUEST,
	message: 'Invalid input',
	payload: { field: 'email', reason: 'required' },
})

HttpResponseCodeMapper

HttpResponseCodeMapper is an enum containing all standard HTTP response status codes (1xx–5xx). Use it with errorHOF or when constructing ErrorBaseModel directly.

import { HttpResponseCodeMapper } from '@beecode/msh-error'

// Available codes include:
// HttpResponseCodeMapper.BAD_REQUEST           // 400
// HttpResponseCodeMapper.UNAUTHORIZED          // 401
// HttpResponseCodeMapper.FORBIDDEN             // 403
// HttpResponseCodeMapper.NOT_FOUND             // 404
// HttpResponseCodeMapper.INTERNAL_SERVER_ERROR // 500
// ... and many more (see source for full list)

Migration

See MIGRATION.md for breaking changes and upgrade instructions.