MongoDB - How can I get the size of a collection using Node.js?

Question

I'm writing a server side code using node.js, I'm trying to get the MongoDB collection size using count method which is not working.

This is my code

var mongo = require('mongodb');
var host =  "127.0.0.1";
var port = mongo.Connection.DEFAULT_PORT;

function getStock(name, callback) {

    var db = new mongo.Db("testDB", new mongo.Server(host, port, {}));
    db.open (function(error){
        console.log("We are connected! " + host + ":" +port);

        db.collection("stocks", function(error, collection){
            console.log("We have a collection");
            **var numOfDocs = db.collection('stocks').count()**
            **console.log("The num of  Docs in our collection is: ",numOfDocs)**
            collection.find({"name":name.toString()}, function(error, cursor) {
                cursor.toArray(function(error, stocks) {
                    if (stocks.length==0) {
                        //console.log("No Stocks found!");
                        callback(false);
                    }
                    else {
                        callback(stocks[0]);
                        //console.log("Found a stock -> ",stocks[0]);
                    }
                });
            });


        });
    });
}

Solution

.count() is an asynchronous function, just like .find() is.

Try the following code:

collection.count({}, function(error, numOfDocs) {
    console.log('I have '+numOfDocs+' documents in my collection');
    // ..
});

The first argument to .count() should be a search query. Since you want to count all documents, I'm passing an empty object {} as a search query.

Comments

[Alex Brodov]

What about the size() method?

[Leonid Beschastny]

@user3502786 there is no size() method in MongoDB. You can use .stats() methods, but it's asynchronous too.

[Leonid Beschastny]

@user3502786 the thing is, all io-related methods in node.js are asynchronous.

[Alex Brodov]

Is it going to give me the same number?

[Leonid Beschastny]

Yes. But it'll give you a lot of other information.

[Alex Brodov]

So count will give me just an integer right? Hoe can i print the whole collection?

[Leonid Beschastny]

Let us continue this discussion in chat.

[Zlatko]

To print the entire collection, fetch the entire collection.maybe you want to use some streaming lib for MongoDB though, if you have a lot of data.