How to save datetime as BSON Date using Node driver? - node.js

Question

I'm using the Node MongoDB driver to collect analytics for my website and send them to MongoLab. How does one insert the current datetime into a document so it can later be used to do aggregation in Mongo?
To be clear, here is the code:
var query = {};
query['date_time'] = new Date();
Db.connect(mongoUri, function (err, db) {
if (!err) {
db.collection(analyticsCollection, function (err, coll) {
if (!err) {
coll.save(query, {safe:true}, function (err, result) {
db.close();
res.send(200,result);
//console.log(result);
});
} else {
res.json(503,{errno:503,msg:'error: collection does not exist.'});
}
});
} else {
res.json(503,{errno:503,msg:'error: database does not exist.'});
}
});
The MongoDB documentation describes how to create a BSON date in the mongo shell, but not in the Node driver and I can't find it in the Node driver docs either.

Answer 1

I found a way to do what I wanted to do. This seems kind of klugey to me, so if anyone can find a better way, please let me know. My solution uses the underscore.js library:
var _ = require('underscore');
vary query = {}
query['foo'] = 'bar'
Db.connect(mongoUri, function (err, db) {
if (!err) {
db.collection(analyticsCollection, function (err, coll) {
if (!err) {
coll.save(_.extend(query,{"datetime":new Date()}), {safe:true}, function (err, result) {
db.close();
res.send(200,result);
//console.log(result);
});
} else {
res.json(503,{errno:503,msg:'error: collection does not exist.'});
}
});
} else {
res.json(503,{errno:503,msg:'error: database does not exist.'});
}
});
Now I can do the aggregation (without needing to use the $project operator):
> db.analytics.aggregate([{$group:{_id:{day:{$dayOfMonth:"$datetime"}}}}])
{ "result" : [ { "_id" : { "day" : 15 } } ], "ok" : 1 }
Hope this helps someone.