Connect synchronously to mongodb

Question

Connect synchronously to mongodb

I would like to connect to mongodb first, then run everything else in my application.

To do it I have to write something like:

MongoClient.connect("mongodb://localhost/test", function(err, connection) {
    if (err) { console.error(err); }
    db = connection;

    var app = express();

    // Include API V1
    require("./apiv1.js")(app, db);

    app.listen(3000, function(err) {
        if (err) { console.error(err); } else { console.log("Started on *:3000"); }
    });
});

This makes my app to be completely indented inside the .connect function... Which looks ugly and takes space while I work on my project.

I think the best solution would be have the MongoDB connection synchronous (even because witout the DB connection my app cannot work so why should I do something while it's connecting?) and then run the rest of my code.

How can I do?

node.js
mongodb

Answer 1

You can't connect to MongoDB synchronously, but you may get rid of this ugly callback from your code.

The best way to do it is to adopt some wrapper around node-mongodb-native driver.

Take a look at the following modules.

mongojs

var mongojs = require('mongojs');
var db = mongojs('localhost/test');
var mycollection = db.collection('mycollection');

mongoskin

var mongo = require('mongoskin');
var db = mongo.db("mongodb://localhost:27017/test", {native_parser:true});

monk

var monk = require('monk');
var db = monk('localhost/test');
var users = db.get('users')

Of course, internally all of them are establishing MongoDB connection asynchronously.

Answer 2

Using the async library, you can aleve some of these issues.

For example in my server startup I do the following :

async.series([
    function(callback){
        // Initialize the mongodb connection and callback on completion in init.
        db.init(function(){
            callback();
        });
    },
    function(callback){
        // Listen on requests etc.
        webServer.init(function(){
            callback();    
        });
    },
    function(callback){
        // Set up anything else that I need
        callback();
    }
]);