NodeJs util.promisify is not a function

Question

I'm trying to promisify a mysql function but when I run it the console shows this error util.Promisify is not a function. This is my code:

var util=			require('util');  var mysql=          require('mysql');    var conection=mysql.createConnection({             				host:'localhost',                     				user:'root',                          				password:'616897',                 				database:'proyect'                      	});        var query = util.promisify(conection.query);        query(data.valida_user).then((rows)=>{  	console.log(rows);  }).catch((error)=>{  	console.log(error);  })

The same error if var query = util.promisify(mysql.query);

I´m new programming but I'm trying to learn.

Answer 1

util.promisify is a part of Node 8.X version. But you can still have a polyfill for the older version of Node.

A polyfill is available to take care of the older version of node servers you’ll be running your application on. It can be installed via npm in the following manner:

npm install util.promisify 

Now you can patch module utl on older versions of Node

const util = require('util'); require('util.promisify').shim();  const fs = require('fs'); const readFileAsync = util.promisify(fs.readFile); 

Quoted from https://grizzlybit.info/blog/nodejs-util-promisify

Answer 2

Unless you're using Node.js 8.x this function won't be defined, that's when it was added to the core Utilities library.

As util is a core Node.js library, you shouldn't have to install it. If you're using Node.js 6.x then use a library like Bluebird which has a promisify function.