userCore1.js

const { query } = require('../util/pg')

/*
Usage:

function handler(req) {
  const id = req.params.id
  const core = new UserCore(req.logger)
  return core.getUser(id)
}

*/
class UserCore {
  constructor(logger) {
    this.logger = logger
  }

  getUser(id) {
    this.logger.log(`Getting user with id ${id} ..`)

    return query('SELECT * FROM users WHERE id = :id', { id })
      .then((rows) => {
        if (rows.length < 1) {
          return null
        }

        return this._userRowToObject(rows[0])
      })
  }

  _userRowToObject(row) {
    this.logger.log('Transforming database row to object ..')

    return {
      id: row.id,
      firstName: row.first_name,
      lastName: row.last_name,
    }
  }
}

module.exports = UserCore

userCore2.js

const { query } = require('../util/pg')

/*
Usage:

function handler(req) {
  const id = req.params.id
  return userCore.getUser(id).bind(req.logger)
}

*/

function getUser(id) {
  this.logger.log(`Getting user with id ${id} ..`)

  return query('SELECT * FROM users WHERE id = :id', { id })
    .then((rows) => {
      if (rows.length < 1) {
        return null
      }

      return _userRowToObject.apply(this, rows[0])
    })
}

function _userRowToObject(row) {
  this.logger.log('Transforming database row to object ..')

  return {
    id: row.id,
    firstName: row.first_name,
    lastName: row.last_name,
  }
}


module.exports = {
  getUser
}

userCore3.js

const { query } = require('../util/pg')

/*
Usage:

function handler(req) {
  const id = req.params.id
  return userCore.getUser(logger, id)
}

*/

function getUser(logger, id) {
  logger.log(`Getting user with id ${id} ..`)

  return query('SELECT * FROM users WHERE id = :id', { id })
    .then((rows) => {
      if (rows.length < 1) {
        return null
      }

      return _userRowToObject(logger, rows[0])
    })
}

function _userRowToObject(logger, row) {
  this.logger.log('Transforming database row to object ..')

  return {
    id: row.id,
    firstName: row.first_name,
    lastName: row.last_name,
  }
}


module.exports = {
  getUser
}

userCore4.js

const { query } = require('../util/pg')

/*
Usage:

function handler(req) {
  const id = req.params.id
  const core = createCore(req.logger)
  return core.getUser(id)
}

*/
function createCore(logger) {
  function getUser(id) {
    logger.log(`Getting user with id ${id} ..`)

    return query('SELECT * FROM users WHERE id = :id', { id })
      .then((rows) => {
        if (rows.length < 1) {
          return null
        }

        return _userRowToObject(rows[0])
      })
  }

  function _userRowToObject(row) {
    logger.log('Transforming database row to object ..')

    return {
      id: row.id,
      firstName: row.first_name,
      lastName: row.last_name,
    }
  }

  return {
    getUser,
  }
}

module.exports = createCore