How to properly handle a transaction with node-pg-pool

node-pg-pool-transaction-handling.js

'use strict'
const { Pool } = require('pg')

// create a pool instance.
// Refer to https://node-postgres.com/api/pool for more info on how to config pool
var pool = new Pool({
  "host": "YOUR_HOST",
  "port": YOURPORT,
  "database": "DBNAME",
  "user": "USERNAME",
  "password": "PASSWORD",
  "max": MAX_POOL_SIZE
});

function foo() {
  return pool.connect()
    .then(client => client.query('begin [your desired isolation level]')
      .then(() => bar(client))
      .then(() => client.query('commit'))
      .catch(err => {
        return client.query('rollback')
          .catch(() => { })
          .then(() => {
            client.release();
            return Promise.reject(err);
          })
      }
      ))
    .catch(err => Promise.reject(err));
}

function bar(client) {
  return client.query('YOUR QUERY')
    .then(() => Promise.resolve('resolve bar'))
    .catch(() => Promise.reject('reject bar'))
}

foo()
  .then((v) => {
    console.log(v)
  })
  .catch((e) => {
    console.log(e)
  })