init event fires before leaving empty state

[fivetanley]

Consider the following model definition:

import Model from "ember-data/model";
import attr from "ember-data/attr";
import { belongsTo, hasMany } from "ember-data/relationships";
import Ember from 'ember';

export default Model.extend({
  title: attr(),
  propSetFromObservingTitle: attr(),

  setPropFromTitle: Ember.observer('title', function() {
      this.set('propSetFromObservingTitle', this.get('title') + 'hi');
  }).on('init')
});

In this example, we have two properties that are DS.attr's. We have propSetFromObservingTitle because we basically want a computed property that also gets serialized to the server.

This code works with normal ember objects, but when we run the following code:

this.store.createRecord('post', {title: 'foo'});

We get the following exception:

VM423 ember.debug.js:31321 Error: Attempted to handle event `didSetProperty` on <post:null> while in state root.empty. Called with {name: propSetFromObservingTitle, oldValue: undefined, originalValue: undefined, value: undefinedhi}.
    at new Error (native)
    at Error.EmberError (https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.6.2/ember.debug.js:15976:21)
    at InternalModel._unhandledEvent (https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.7.0/ember-data.js:2623:13)
    at InternalModel.send (https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.7.0/ember-data.js:2501:14)
    at Class.set (https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.7.0/ember-data.js:13361:31)
    at Descriptor.computedPropertySet [as _set] (https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.6.2/ember.debug.js:14654:28)
    at Descriptor.computedPropertySetWithSuspend [as setWithSuspend] (https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.6.2/ember.debug.js:14634:19)
    at Descriptor.computedPropertySetEntry [as set] (https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.6.2/ember.debug.js:14612:17)
    at Object.set (https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.6.2/ember.debug.js:20348:12)
    at Class.set (https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.6.2/ember.debug.js:34672:38)

Example on Ember Twiddle: https://ember-twiddle.com/415538f55bbaa01ca95067ec0e890d43?openFiles=models.post.js%2C

[runspired]

The issue here is that when we call create we don't do so with the initial or current data, but should. Looking through the code this afternoon I think this is fixable.

[stefanpenner]

https://github.com/emberjs/data/blob/master/addon/-private/system/store.js#L368-L377 should be unified to load + initial the object in one go