How to get mongoDB collection size in node js?

Question

I'm trying to connect to a mongoDB DB, and make some processes on a collection, and close the collection when all the collection items were processed. when I'm trying to receive array.length, I get undefined.

Db = require('mongodb').Db;
Server = require('mongodb').Server;
const db = new Db(DB_NAME, new Server(HOST, PORT));
// connect to mongoDB
db.open(function (err, db) {
  const Collection = db.collection(COLLECTION_NAME);
  var items = Collection.find({});
  var itemsLength = items.lebgth;
  var itemsProcessed = 0;
  items.forEach((item, index, array) => {
    // some process like:
    Collection.update({query}, {set}, callback)
    itemsProcessed++;
    if(itemsProcessed == array.length){
      db.close();
      // close connection if all items were processed
    }
  });
});

Is there any other way to do it?

items is cursor so you need to execute like: var items = Collection.find({}).toArray(); — Shaishab Roy
– Shaishab Roy, Commented Dec 15, 2016 at 9:45

user6307701 · Accepted Answer · 2016-12-15 09:21:41Z

2

Just use db.collection.count()

answered Dec 15, 2016 at 9:21

user6307701

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GilZ · Accepted Answer · 2016-12-15 10:58:11Z

1

EDIT:

You can use the optional callback of forEach, as documented here:

items.forEach((item) => {
    // some process...
}, (err) => db.close()); // close connection if all items were processed

edited Dec 15, 2016 at 10:58

answered Dec 15, 2016 at 10:27

GilZ

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4 Comments

Ruchy Over a year ago

in this case items.hasNext() is a promise object. how can I do somthing like this: items.hasNext((has) => { if(!has) db.close(); } );

Ruchy Over a year ago

it works just partly, the callback raised up before processing all elements.

GilZ Over a year ago

Sounds weird. Are you doing anything asynchronous inside the loop?

GilZ Over a year ago

Well, that was an important bit of information to mention in the original question... I suggest that in the forEach loop you'd build the update query (that way it can be a single update with multi=true instead of many update calls), call update in the forEach callback, and call db.close in the update callback. In addition, I suggest you'd edit your question and its title to better reflect what you're trying to do.

Mohsen ZareZardeyni · Accepted Answer · 2016-12-15 09:25:42Z

0

check this!

Collection.stat()

answered Dec 15, 2016 at 9:25

Mohsen ZareZardeyni

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