Removing documents from a mongodb collection from node.js

Question

I'm totally new to mongoDB and not experienced with Node.js so please excuse if the code below is far from perfect.

The goal is to remove a document from a collection, referenced by its _id. The removal is done (checked in mongo shell), but the code does not end (running node myscript.js doesn't get my shell back). If I add a db.close() I get { [MongoError: Connection Closed By Application] name: 'MongoError' }.

var MongoClient = require("mongodb").MongoClient;
var ObjectID = require("mongodb").ObjectID;

MongoClient.connect('mongodb://localhost/mochatests', function(err, db) {
    if (err) {
        console.log("error connecting");
        throw err;
    }
    db.collection('contacts', {}, function(err, contacts) {
        if (err) {
            console.log("error getting collection");
            throw err;
        }
        contacts.remove({_id: ObjectID("52b2f757b8116e1df2eb46ac")}, {safe: true}, function(err, result) {
            if (err) {
                console.log(err);
                throw err;
            }
            console.log(result);
        });
    });
    db.close();
});

Do I not have to close the connection? What's happening when I'm not closing it and the program doesn't end?

Thanks!

Answer 1

Welcome to asynchronous style:

• You should not use throw for callback, throw is good for function stack
• db.close() should be in the callback, after removing is done.

Example:

MongoClient.connect('mongodb://localhost/mochatests', function(err, db) {
    db.collection('contacts', {}, function(err, contacts) {
        contacts.remove({_id: ObjectID("52b2f757b8116e1df2eb46ac")}, function(err, result) {
            if (err) {
                console.log(err);
            }
            console.log(result);
            db.close();
        });
    });
});