mongojs

mongojs

A node.js module for mongodb, that emulates the official mongodb API as much as possible. It wraps mongodb-native. It is available through npm:

npm install mongojs

Usage

mongojs is very simple to use:

var mongojs = require('mongojs');
var db = mongojs(connectionString, [collections]);

The connection string should follow the format desribed in the mongo connection string docs. Some examples of this could be:

// simple usage for a local db
var db = mongojs('mydb', ['mycollection']);

// the db is on a remote server (the port default to mongo)
var db = mongojs('example.com/mydb', ['mycollection']);

// we can also provide some credentials
var db = mongojs('username:[e-mail]/mydb', ['mycollection']);

// connect now, and worry about collections later
var db = mongojs('mydb');
var mycollection = db.collection('mycollection');

After we connected we can query or update the database just how we would using the mongo API with the exception that we use a callback The format for callbacks is always callback(error, value) where error is null if no exception has occured.

// find everything
db.mycollection.find(function(err, docs) {
	// docs is an array of all the documents in mycollection
});

// find everything, but sort by name
db.mycollection.find().sort({name:1}, function(err, docs) {
	// docs is now a sorted array
});

// iterate over all whose level is greater than 90.
db.mycollection.find({level:{$gt:90}}).forEach(function(err, doc) {
	if (!doc) {
		// we visited all docs in the collection
		return;
	}
	// doc is a document in the collection
});

// find all named 'mathias' and increment their level
db.mycollection.update({name:'mathias'}, {$inc:{level:1}}, {multi:true}, function(err) {
	// the update is complete
});

// find one named 'mathias', tag him as a contributor and return the modified doc

db.mycollection.findAndModify({
	query: { name: 'mathias' },
	update: { $set: { tag:'maintainer' } },
	new: true
}, function(err, doc) {
	// doc.tag === 'maintainer'
});


// use the save function to just save a document (the callback is optional for all writes)
db.mycollection.save({created:'just now'});

If you provide a callback to find or any cursor config operation mongojs will call toArray for you

db.mycollection.find({}, function(err, docs) { ... });

db.mycollection.find({}).limit(2).skip(1, function(err, docs) { ... });

is the same as

db.mycollection.find({}).toArray(function(err, docs) { ... });

db.mycollection.find({}).limit(2).skip(1).toArray(function(err, docs) { ... });

For more detailed information about the different usages of update and quering see the mongo docs

Streaming cursors

As of 0.7.0 all cursors are a readable stream of objects.

var JSONStream = require('JSONStream');

// pipe all documents in mycollection to stdout
db.mycollection.find({}).pipe(JSONStream.stringify()).pipe(process.stdout);

Notice that you should pipe the cursor through a stringifier (like JSONStream) if you want to pipe it to a serial stream like a http response.

Tailable cursors

If you are using a capped collection you can create a tailable cursor to that collection by adding tailable:true to the find options

var cursor = db.mycollection.find({}, {}, {tailable:true, timeout:false});

// since all cursors are streams we can just listen for data
cursor.on('data', function(doc) {
	console.log('new document', doc);
});

Note that you need to explicitly set the selection parameter in the find call.

Replication Sets

Mongojs can also connect to a mongo replication set by providing a connection string with multiple hosts

var db = mongojs('rs-1.com,rs-2.com,rs-3.com/mydb?slaveOk=true', ['mycollection']);

For more detailed information about replica sets see the mongo replication docs

License

MIT