@douglasmuraoka/express-error-handler NPM

express-error-handler

Fast, opinionated, minimalist error handler for Express APIs.

// Imagine you have your errors defined...
class OMGServiceError extends Error {}
class MehError extends Error {}
class InvalidUserDataError extends Error {
  constructor () {
    super('Oh noes!')
  }
}

const express = require('express')
const errorHandler = require('express-error-handler')
const mongoose = require('mongoose')
const app = express()

// And any of your services throws it...
app.get('/omg-service', () => {
  throw new OMGServiceError()
})

app.get('/meh', () => {
  throw new MehError()
})

app.post('/user', () => {
  throw new InvalidUserDataError()
})

const Cat = mongoose.model('Cat', new mongoose.Schema({
  name: {
    type: String,
    required: true
  },
  age: {
    type: Number,
    min: 0,
    max: 9999
  }
}))

app.get('/cat', (req, res, next) => {
  new Cat({
    age: -1
  }).save().catch(next)
})

// You can define this error handler...
app.use(errorHandler({
  OMGServiceError: {
    errorCode: 666,
    statusCode: 418,
    message: 'A wild TEAPOT appeared!'
  },
  MehError: 'Meh!',
  InvalidUserDataError: {
    errorCode: 666,
    statusCode: 400,
    message: 'Useless data',
    validate: err => ({
      foo: `${err.message} Obviously required`,
      bar: `${err.message} Should be bigger than 15 😉`
    })
  }
}))

app.listen(3000)

And have all your error responses standardized :)

curl http://localhost:3000/omg-service
# {"errorCode":666,"message":"A wild TEAPOT appeared!"}
# StatusCode 418

curl http://localhost:3000/meh
# {"message":"Meh!"}
# StatusCode 500

curl -X POST http://localhost:3000/user
# {"errorCode":666,"message":"Useless data","validation":{"foo":"Oh noes! Obviously required","bar":"Oh noes! Should be bigger than 15 😉"}}
# StatusCode 400

# It also handles Mongoose validation errors :)
curl http://localhost:3000/cat
# {"message":"Operation failed due to invalid data","validation":{"name":"required","age":"minimum value: 0"}}
# StatusCode 400

Installation

This is a Node.js module available through the npm registry.

npm install express-error-handler

yarn add express-error-handler

Features

STANDARDIZED ERROR RESPONSES
A simple way to map all Errors thrown by your Express application to a HTTP statusCode and a simple, but yet, (hopefully) useful JSON response
No need to waste your time thinking about API error response patterns
Includes a built-in Mongoose validation error handler! 🙌🏼

Quick Start

Setup your Express API, then install this as a dependency:

npm install express-error-handler

Map errors you want to be handled:

class UserCashIsGone extends Error {}

const express = require('express')
const errorHandler = require('express-error-handler')
const app = express()

app.get('/check-fund', () => {
  throw new UserCashIsGone()
})

app.use(errorHandler({
  UserCashIsGone: {
    errorCode: 666,
    statusCode: 402,
    message: 'We dont know what happened. Please try again later...'
  }
}))

app.listen(3000)

And everything handled by this error handler should look pretty similar!