Promise Wrappers

In addition to errback interface there is thin wrapper to expose Promise-based api

Basic Promise

/* eslint-env es6 */
const mysql = require('mysql2/promise'); // or require('mysql2').createConnectionPromise
mysql
  .createConnection({
    /* same parameters as for non-promise createConnection */
  })
  .then((conn) => conn.query('select foo from bar'))
  .then(([rows, fields]) => console.log(rows[0].foo));

const pool = require('mysql2/promise').createPool({}); // or require('mysql2').createPoolPromise({}) or require('mysql2').createPool({}).promise()
pool
  .getConnection()
  .then((conn) => {
    const res = conn.query('select foo from bar');
    conn.release();
    return res;
  })
  .then((result) => {
    console.log(result[0][0].foo);
  })
  .catch((err) => {
    console.log(err); // any of connection time or query time errors from above
  });

ES7 Async Await

async function example1() {
  const mysql = require('mysql2/promise');
  const conn = await mysql.createConnection({ database: test });
  const [rows, fields] = await conn.execute('select ?+? as sum', [2, 2]);
  await conn.end();
}

async function example2() {
  const mysql = require('mysql2/promise');
  const pool = mysql.createPool({ database: test });
  // execute in parallel, next console.log in 3 seconds
  await Promise.all([
    pool.query('select sleep(2)'),
    pool.query('select sleep(3)'),
  ]);
  console.log('3 seconds after');
  await pool.end();
}

Explicit Resource Management (await using)

With Explicit Resource Management, connections and pools are automatically cleaned up when they go out of scope — no need to manually call .end() or .release().

import mysql from 'mysql2/promise';

{
  await using conn = await mysql.createConnection({ database: test });
  const [rows, fields] = await conn.execute('select ?+? as sum', [2, 2]);
  // conn.end() is called automatically when leaving the scope
}

import mysql from 'mysql2/promise';

{
  await using pool = mysql.createPool({ database: test });

  // execute in parallel, next console.log in 3 seconds
  await Promise.all([
    pool.query('select sleep(2)'),
    pool.query('select sleep(3)'),
  ]);
  console.log('3 seconds after');
  // pool.end() is called automatically when leaving the scope
}

import mysql from 'mysql2/promise';

const pool = mysql.createPool({});

{
  await using conn = await pool.getConnection();
  const res = await conn.query('select foo from bar');
  console.log(res[0][0].foo);
  // conn.release() is called automatically when leaving the scope
}

dica

await using and using leverage Explicit Resource Management to automatically call .end() or .release() when the variable goes out of scope, so you never forget to clean up connections.

With CO

const mysql = require('mysql2');
const co = require('co');
co(function* () {
  const c = yield mysql.createConnectionPromise({
    user: 'root',
    namedPlaceholders: true,
  });
  const rows = yield c.query('show databases');
  console.log(rows);
  console.log(yield c.execute('select 1+:toAdd as qqq', { toAdd: 10 }));
  yield c.end();
});

Examples in /examples/promise-co-await