app.js

const { MONGO_DB_CONNECTION, NODE_ENV, PORT } = process.env
const express = require('express')
const mongoose = require('mongoose')
const app = express()

// Database Connection
if (MONGO_DB_CONNECTION) {
  mongoose.connect(MONGO_DB_CONNECTION, { useNewUrlParser: true })
  console.log('Connected to database...')
} else {
  console.log('Could not connect to database!')
}

// Application-level Middleware
if (NODE_ENV === 'development') app.use(require('morgan')('dev'))
app.use(require('body-parser').json())

// Routes
app.use('/api/parties', require('./api/routes/parties'))

// Not Found Handler
app.use((req, res, next) => {
  const error = new Error(`Could not ${req.method} ${req.path}`)
  error.status = 404
  next(error)
})

// Error Handler
app.use((err, req, res, next) => {
  if (NODE_ENV === 'development') console.error(err)
  const { message, status } = err
  res.status(status).json({ status, message })
})

// Open Connection
const listener = () => console.log(`Listening on Port ${PORT}!`)
app.listen(PORT, listener)