Node JS MongoDB collection.find.toArray returns no value

Question

I'm building a website that lets people write sticky notes and print it to them on the screen. I want to store the sticky notes inside a mongoDB with a db called stickyNotes and a collection called stickyNotes which currently has two documents.

I have a variable called stickyNotes which suppose to get the documents from the stickyNotes collection on the db but when I use the collection.find.toArray from the mongodb library to enter the documents to the stickyNotes variable in an asynchronous way, it shows an empty array value.

This is my server.js file:

const express = require("express");
const mongo = require("mongodb").MongoClient;
const app = express();

let stickyNotes = [];

//mongodb get all sticky notes
const mongoUrl = "mongodb://localhost:27017";
mongo.connect(mongoUrl, { useNewUrlParser: true }, async function(
  err,
  connection
) {
  if (err) {
    console.error(err);
  } else {
    console.log("Succesfully connected to the database");
    const db = connection.db("stickyNotes");
    const stickyNotesCollection = db.collection("stickyNotes");
    stickyNotes = await stickyNotesCollection.find({}).toArray();
  }
  connection.close();
});

console.log(stickyNotes);

app.use(express.static("./src/public"));

app.get("/sticky-notes", (req, res) => {
  console.log("Got a request for sticky notes");
  res.json(stickyNotes);
});

const port = 3000;
app.listen(port, () => {
  console.log(`App is running on port ${port}`);
});

console.log(stickyNotes) is logging empty array because it's executing before the query. Here the DB query is asynchronous. Other than that your script is working fine. Check out blog.risingstack.com/node-hero-async-programming-in-node-js to understand nodejs asynchronous behaviour — Subbu
– Subbu, Commented Jul 6, 2019 at 16:52
Just put the console.log() inside the async function, after you awaited the toArray() promise - not outside of the connect function. — Bergi
– Bergi, Commented Jul 6, 2019 at 18:37
Possible duplicate of Node.js MongoDB collection.find().toArray returns nothing — Yilmaz
– Yilmaz, Commented Jul 6, 2019 at 18:43
@Bergi I tried to do this indise the async function after the await and it still shows stickyNotes is an empty array... — nadav atar
– nadav atar, Commented Jul 6, 2019 at 19:08

Matteo Ponzo · Accepted Answer · 2019-07-06 18:15:53Z

0

Can try with:

stickyNotesCollection.find({}, (err, result) => {
    if (err) throw err;
    stickyNotes = result;
  });

or find result in array:

collection.find().toArray(function(err, result) {
    console.log(result);
});

or iterate:

collection.find().each(function(err, result) {
    //once result
});

edited Jul 6, 2019 at 18:15

answered Jul 6, 2019 at 16:45

Matteo Ponzo

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4 Comments

nadav atar Over a year ago

Thanks for the answer, I tried it and when I console.log() stickyNotes after the query executes it shows alot of metadata which I believe is a MongoDB Cursor, you have any idea how to fix it?

Matteo Ponzo Over a year ago

I changed the answer

nadav atar Over a year ago

I tried all of those and the first two didnt work and the last one said "Cursor each is deprecated, use cursor ForEach". Any idea?

Matteo Ponzo Over a year ago

stickyNotesCollection.find().forEach((result) => { /*result*/ }, (err) =>{ /*error*/ });

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