server.js

const express = require('express')
const next = require('next')
const { postgraphql } = require('postgraphql')


module.exports = function (port, callback) {
  const dev = isDevEnvironment()
  const app = next({ dev })
  const handle = app.getRequestHandler()

  return app.prepare().then(() => {
    const server = express()

    //   server.use(
    //     postgraphql(
    //       {
    //         host: 'localhost',
    //         database: 'sq_test',
    //         port: 5432,
    //         user: 'postgres',
    //         password: process.env.PGPASSWORD
    //        },
    //       'valueflows',
    //       { graphiql: true }
    //     )
    //   )
    //

    server.get('*', (req, res) => {
      return handle(req, res)
    })

    if (!callback) {
      return new Promise((resolve, reject) => {
        server.listen(port, err => {
          if (err) reject(err)
          console.log(`> Ready on http://localhost:${port}`)
          resolve()
        })
      })
    }

    server.listen(port, err => {
      if (err) callback(err)
      console.log(`> Ready on http://localhost:${port}`)
      callback(null)
    })
  })
}

function isDevEnvironment () {
  if (process.env.NODE_ENV === 'production') return false
  if (process.env.NODE_ENV === 'test') return false
  return true
}