hapi-logging-es6-spreading-method-does-not-work.js

const Hapi = require('@hapi/hapi')
;(async () => {
  const server = Hapi.server({
    port: 3000
  })

  server.events.on('log', logObject => {
    console.log(JSON.stringify(logObject))
  })

  server.route({
    path: '/ip',
    method: 'GET',
    handler (request) {
      // this works as expected
      request.server.log('debug', 'got request')
      /*
        but the following codes won't work, got error below instead
        Debug: internal, implementation, error 
        TypeError: Cannot read property '_core' of undefined

        why?
      */
      // const {
      //   server: { log }
      // } = request
      // log('debug', 'got request')

      return {
        ip: request.info.remoteAddress
      }
    }
  })
  await server.start()
  console.log('start started at %s', server.info.uri)
})()

reason-why-spreading-form-does-not-work.js

// Logger.js
const levelMap = {
  info: 1,
  warning: 2,
  error: 3
}

class Logger {
  constructor (options) {
    // from low to high: info, warning, error
    this.logLevel = (options && options.logLevel) || 'warning'
  }

  _logger (data) {
    console.log(
      '[%s] %s',
      new Date().toLocaleString(),
      typeof data === 'object' ? JSON.stringify(data) : data
    )
  }

  log (info, level) {
    if (levelMap[level] < levelMap[this.logLevel]) {
      return
    }
    this._logger(info)
  }
}

module.exports = Logger

// app.js
const Logger = require('./logger')
const logger = new Logger()

// this works
logger.log({hello: 'world'}, 'warning')

// this doesn't
const {log} = logger
log({hello: 'world'}, 'warning')

// reason being, Logger->log accesses member only attribute (this.logLevel) and method (this._logger)