Question

I am accessing MongoDB documents with a node.js web-front-end while in developement.

I got now following document:

{
   "_id": ObjectID("500abe6a25dff13c7c000001")
    , "username": "kyogron"
    , "email": "[e-mail]"
    , "contacts": [ObjectID("500abe6a2543213c7c000002")] // this should contain other user's id
}

I now want to add another user_id to the contacts array manually, before implementing the feature in the front-end.

As you see above I alread tried this using the ObjectID keyword but this didn’t work…

Answer 1

This worked for me from the MongoDB shell, I’m using $addToSet instead of $push because I assume you want to avoid dupes:

var o = new ObjectId();
db.foo.update({}, {$addToSet : {"contacts" : o}});
var o = new ObjectId();
db.foo.update({}, {$addToSet : {"contacts" : o}});

That gave me a document that looks like this (my foo collection only contained your sample, so I didn’t have to have a specific matching criteria):

{
    "_id" : ObjectId("500c2118c78bb07bfbb69eb3"),
    "contacts" : [
        ObjectId("500c20efc78bb07bfbb69eb2"),
        ObjectId("500c227ac78bb07bfbb69eb6")
    ],
    "email" : "[e-mail]",
    "username" : "kyogron"
}