Question

I have a MongoDocument X which has some instances of MongoEmbeddedDocument Y.

I now want to add an extra embeddeddocument Y to my X collection. I’ve tried the following code:

var mongo = db.x.findOne();
mongo.y = { title:"test" }
db.x.save(mongo)

The problem is that that piece of code will deleted my entire collection of y embeddeddocuments that I had. Is there someway I can add one without deleting the existing ones?

Answer 1

Assuming you’re using an array to store your y, you probably want to do a $push, something like:

var mongo = db.x.findOne();
db.x.update({_id:mongo._id}, {$push:{y:{title:"test2"}}});

If you want to save the whole record again, you can do it closer to what you were trying:

var mongo = db.x.findOne();
mongo.y.push({title:"test2"});
db.x.save(mongo);

But $push is probably better, and you can do it in a single update command.