Node.js MongoDB collection.find().toArray returns nothing

Question

Although I found similar questions to mine, I couldn't solve the problem on my own.

In my '../models/user' model I want to find all users and put them into array, and return that array to the controller(where I will use the info).

Here is my code:

var mongoDatabase = require('../db');
var database = mongoDatabase.getDb();

function find() {
    var test;
    database.collection("customers").find().toArray( function(err, docs) {
        if(err) throw err;
        console.log(docs); //works fine
         //I'd like to return docs array to the caller
        test = docs;
    });

    console.log(test); //test is undefined  
}

module.exports = {
    find
};

I also noticed, that 'console.log(test)' goes before 'console.log(docs)'. I tried passing 'docs' argument as function parameter to 'find', but without result.

Judging from the documents of MongoDB you cannot pass arguments to the toArray why don't you simply do ```test = database.customers.find().toArray()``` — Ozan, Jul 15 '17 at 13:54
@Petar D. Well I just tested in my local development and it did return all the documents. I am not sure what's causing it. Why don't you use mongoose ? — Ozan, Jul 15 '17 at 13:58
@Ozan I'll start using Mongoose soon, but first I'd like to learn the basics — Petar D., Jul 15 '17 at 14:02
You can try this, var mongoDatabase = require('../db'); var database = mongoDatabase.getDb(); function find() { return database.collection("customers").find().toArray(); } module.exports = { find }; — Pavneet Kaur, Apr 05 '21 at 20:22

Kamesh · Accepted Answer · 2017-07-15T14:12:58.740

15

The best way is to use Promises. Do it like this.

function getUsers () {
  return new Promise(function(resolve, reject) {
     database.collection("customers").find().toArray( function(err, docs) {
      if (err) {
        // Reject the Promise with an error
        return reject(err)
      }

      // Resolve (or fulfill) the promise with data
      return resolve(docs)
    })
  })
}

edited Jul 15 '17 at 14:12

answered Jul 15 '17 at 14:03

Kamesh

1,122
9
12

What modules should I include? Is that 'jQuery'? – Petar D. Jul 15 '17 at 14:06
No, I have edited it, You should install an npm module 'q' – Kamesh Jul 15 '17 at 14:07
1

There is no need to add yet another module as Node.js has been supporting native Promises since around version 0.12 by itself. – str Jul 15 '17 at 14:09
Thanks for pointing this out. I have edited my answer. – Kamesh Jul 15 '17 at 14:13
1

@PetarD. You can also use the above code if you don't want to include the module – Kamesh Jul 15 '17 at 14:13
@Kamesh thank you, now the last thing I want to do is: 'var usersInfo = users.find(); console.log(usersInfo');' and it says 'Promise {'}. Can you help with that too :D – Petar D. Jul 15 '17 at 14:20
Can you post more of your code? Where are you writing these statements? – Kamesh Jul 15 '17 at 14:21
In my router, 'router.get('/', function(req, res) { var usersInfo = users.find(); console.log(usersInfo); res.render("myview", { data: usersInfo }); }' – Petar D. Jul 15 '17 at 14:27
Is users a mongo model? In that case you need to have a callback in your find as well. users.find(function(err, docs){ //resolve promise here with your data }) – Kamesh Jul 15 '17 at 14:29
but If we console the docs it will say undefine. – Pooja Khatri Jan 27 '20 at 13:17
That is why you need to use console.log inside the definition for function passed to toArray – Kamesh Jan 27 '20 at 13:23
How can i write this in python3? @Kamesh – Amogh Katwe Oct 27 '20 at 14:40

Node.js MongoDB collection.find().toArray returns nothing

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