mongoDB - Update query adding an array document to an existing document

Question

The userlist collection contains documents of the following format.

{
        "_id" : ObjectId("5381d32ce72cc794166eede2"),
        "name" : "Haseeb",
        "password" : "dgkhan",
        "email" : "hasseeb@yahoo.com",
        "address" : "237 D, Faisal Town , Lahore",
        "phone" : "5162806"
}

I intend to add another member in the existing document such that the resultant document looks like this.

{
            "_id" : ObjectId("5381d32ce72cc794166eede2"),
            "name" : "Haseeb",
            "password" : "dgkhan",
            "email" : "hasseeb@yahoo.com",
            "address" : "237 D, Faisal Town , Lahore",
            "phone" : "5162806",
            "purchases" : [{
                "itemID": xyz,
                "quantity": 142
            },
            {
                "itemID": kjh,
                "quantity": 987
            }
            }]

}

For this I have written the following mongoskin query, but it is not performing any updates.

db.collection('userlist').update(
                {_id:req.session._id},
                 {
                    '$push': { purchases: {
                        itemID: item.ID,
                        quantity: item.quantity
                    }
                }
            }, function(err) {
                if (err) throw err;
                    console.log('Updated!');
            });
        }

Value of req.session._id = 5381d32ce72cc794166eede2 i.e a valid _id field of a docuemnt in my collection whereas item.ID and item.quantity are also valid strings. Any help would be really appreciated.

Answer 1

I'm more familiar with Mongoose, but looking at the docs you could probably either use:

collection.updateById(req.session._id, ...)

or

collection.update({_id: toObjectID(req.session_id)}, ...)