Ember-data "Cannot call method 'hasOwnProperty' of undefined"

Question

I have the following Ember.js model:

Filters.Milestone = DS.Model.extend({
    id: DS.attr('string'),
    name: DS.attr('string')
});

In my app.js I have the following settings for the model (loaded prior to the model):

Filters.MilestoneSerializer = DS.RESTSerializer.extend();
Filters.MilestoneAdapter = DS.RESTAdapter.extend({
    namespace: "ember"
});

When loading the page, an AJAX call to the milestones list is done. The following JSON is returned:

{
    "milestones": [
        {
            "id": "1",
            "name": "Test Milestone #1"
        }
    ]
}

When the JSON is loaded, the following error is returned:

TypeError: Cannot call method 'hasOwnProperty' of undefined
    at e (http://sandbox.local/ember/js/libs/ember-data.js:8:30934)
    at null.<anonymous> (http://sandbox.local/ember/js/libs/ember-data.js:8:31181)
    at ComputedPropertyPrototype.set (http://sandbox.local/ember/js/libs/ember-1.4.0.js:4903:18)
    at new Class (http://sandbox.local/ember/js/libs/ember-1.4.0.js:12652:18)
    at Function.Mixin.create.create (http://sandbox.local/ember/js/libs/ember-1.4.0.js:13104:12)
    at Ember.Object.extend.buildRecord (http://sandbox.local/ember/js/libs/ember-data.js:10:2880)
    at Ember.Object.extend.recordForId (http://sandbox.local/ember/js/libs/ember-data.js:9:31214)
    at Ember.Object.extend._load (http://sandbox.local/ember/js/libs/ember-data.js:10:2048)
    at Ember.Object.extend.push (http://sandbox.local/ember/js/libs/ember-data.js:10:2450)
    at null.<anonymous> (http://sandbox.local/ember/js/libs/ember-data.js:10:2701)

What am I doing wrong? I have tried following the same structure as https://github.com/emberjs/data/blob/master/packages/ember-data/tests/integration/adapter/rest_adapter_test.js#L465. If I rename the milestones key it says that no model could be found for the new key, so something must be right :-)

Thanks in advance.

Edit

The route that I use is the following:

Filters.FiltersRoute = Ember.Route.extend({
    model: function() {
        return this.store.find('milestone')
    }
});

If this.store.find('milestone') is not called the error doesn't occur. Also, if I use the FixtureAdapter instead of the RESTAdapter, the error still occurs. So it seems that this might be related to the model, not the data source.

Answer 1

The problem was caused by the id attribute in the model. Apparently this should not be part of the model.