Common Express Helpers

Reusable helpers and middlewares for express server projects.

Connect Mongo Db

Helper function to connect to a Mongo Db database using Mongoose.

Parameters

Object of parameters to pass to the function

• mongoOptions Type: Object - Options to pass to Mongoose

• mongoUri Type: String - Mongo Db uri to connect

• verbose Type: Boolean - Print the Mongo Db Uri in the console, do not use this in production

Usage

import { connectMongoDb } from '@lgdweb/common-express-helpers'

const mongoOptions = {
  useNewUrlParser: true,
  useUnifiedTopology: true
}
const mongoUri = 'mongodb://localhost:27017/dbName'
const verbose = process.env.NODE_ENVIRONMENT === 'development'

connectMongoDb({ mongoOptions, mongoUri, verbose })

Setup Close On Exit

Helper function that closes properly an Express server.

Parameters

An instance of Express.

Usage

import { setupCloseOnExit } from '@lgdweb/common-express-helpers'
import express from 'express'

const app = express()
const port = process.env.PORT || 5000

const server = app.listen(port, '0.0.0.0', () =>
  console.info(`Server is listening on http://localhost:${port}`)
)

setupCloseOnExit(server)

Get Details For Error

Helper function that returns formated http error details based on some error types and using http-errors package.

Parameters

A standard Error object.

Usage

This helper function is used internally in the errorHandler middleware

Error Handler Middleware

Middleware for handling errors from Express app that returns a formated error with some details base on the error type.

Parameters

Standard parameters for Express middlewares:

• error Type: Error - Standard Error or HttpError instance for nice formated error details
• req Type: Request - The request object from Express
• res Type: Response - The Response object from Express
• next Type: Next - The Next object from Express

Usage

import { errorHandler } from '@lgdweb/common-express-helpers'
import express from 'express'

const app = express()

app.use(errorHandler)

const port = process.env.PORT || 5000

app.listen(port, '0.0.0.0', () =>
    console.info(`Server is listening on http://localhost:${port}`)

Request Validator Middleware

Middleware that validates a request using Express Validator and returns well formatted validation errors or continue if no error.

Parameters

Validation rules same as express-validator package.

Usage

import { errorHandler, requestValidator } from '@lgdweb/common-express-helpers'
import express from 'express'
import { body } from 'express-validator'

const app = express()

app.use(express.json())

const emailField = [
  body('email').exists().withMessage('Email field is required'),
  body('email')
    .notEmpty()
    .withMessage('Email must not be empty')
    .bail()
    .isEmail()
    .withMessage('Email must be a valid email')
    .optional()
    .normalizeEmail()
]

app.post('/api/users', requestValidator(emailField), async (req, res) => {
  const { email } = req.body

  res.status(201).json({ message: `User created with email: ${email}` })
})

app.use(errorHandler)

const port = process.env.PORT || 5000

app.listen(port, '0.0.0.0', () => console.info(`Server is listening on http://localhost:${port}`))

Not Found Middleware

Middleware that handles all routes that not match and returns a 404 NotFound error.

Parameters

Standard Express middleware parameters.

Usage

import { errorHandler, notFound } from '@lgdweb/common-express-helpers'
import express from 'express'

const app = express()

app.all('*', notFound)
app.use(errorHandler)

const port = process.env.PORT || 5000

app.listen(port, '0.0.0.0', () => console.info(`Server is listening on http://localhost:${port}`))