Question

I am working with mongoLab and the model id looks like this

"_id": {
  "$oid": "50f9a0f5e4b007f27f766cf3"
},

I am using the idAttribute to set the model id to _id and everything works fine until I attempt to update the model.

Because the _id attribute exists in the model, I am getting an error when I attempt to insert.

Do I need to remove the attribute _id from my attributes? I was under the assumption that the magic of Backbone would clean up the attributes appropriately

Answer 1

You would need to remove the _id attribute.

In the MongoLab REST API, the id isn’t part of the data payload itself, but that isn’t the case for all backends. It probably makes more sense for Backbone to assume that the id should be present in the payload, than it would to assume it should not.

That being said there’s no real nice way to get Backbone to clean the id from the payload automatically. Your best bet without monkeypatching/rewriting too much of the code would probably be to override Model#toJSON, something akin to:

Backbone.Model.prototype.toJSON = function (options) {
  var attrs = _.clone(this.attributes);
  // In this case you'd have to pass `includeId: true` to `toJSON` when you
  // actually *want* the _id in the output.
  return options && options.includeId ? attrs : _.omit(attrs, '_id');
};

You could also monkeypatch sync, something like:

var sync = Backbone.sync;
Backbone.sync = function (method, model, options) {
  options || (options = {});
  // if options.attrs is present, Backbone will use it over dumping toJSON
  if (!options.attrs) options.attrs = _.omit(model.attributes, '_id');
  return sync.call(Backbone, method, model, options);
};