Returning Promise { undefined } in NodeJS when making a function call

Question

I am trying to call a function and wait till the function gets data before further statements get executed. I am new to node js and async/await and promises. I tried some solutions but doesn't work it always returning Promise { undefined }.

If I run code without using a separate function it works fine. but I have to use functions here for database connection.

here's my code.

db.js

const mongoClient = require('mongodb').MongoClient;

const db_url = "mongodb_url";
const database_name = "mydb";

module.exports.GetAllUsersData = async function (){
    mongoClient.connect(db_url,{ useUnifiedTopology: true },function(err,dbserver){
        if(err) throw err;
        var mydb = dbserver.db(database_name);
        mydb.collection('users').find({}).toArray(function(err,results){
            console.log(results); //I am getting data here
            return Promise.resolve(results);
            
        });
    });
}

app.js

const express = require('express');

const db = require('./db.js');

//
const app = express();
app.set(express.static('public'));
app.set('view engine','ejs');
var urlencodeparser = express.urlencoded({extended:false});


app.get('/',function(req,res){
   
    var results =  db.GetAllUsersData();
    results.then(console.log(results)); //getting promise {undefined} here
    res.render('home.ejs',{users:results})
})

console.log('connected...')
app.listen(9000);

Answer 1

You can make it work by rewriting your GetAllUserData function as follows:

module.exports.GetAllUsersData = function () {
    return new Promise((resolve, reject) => {
        mongoClient.connect(db_url,{ useUnifiedTopology: true },function(err,dbserver){
            if(err) reject(err);
            var mydb = dbserver.db(database_name);
            mydb.collection('users').find({}).toArray(function(err,results){
                console.log(results); //I am getting data here
                resolve(results);                
            });
        });
    });
});