Embedded Playground

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  serialized: Ember.computed('model', function() {
    const serialized = this.get('model').serialize({ includeId: true });
    return JSON.stringify(serialized, null, 2);
  })
});

models.embeddee.js

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

export default Model.extend({
  name: attr('string')
});

models.embedder.js

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

export default Model.extend({
  embeddees: hasMany('embeddee')
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  beforeModel() {
    const first = this.store.createRecord('embeddee', { id: 1, name: 'one' });
    const second = this.store.createRecord('embeddee', { id: 2, name: 'two' });
    this.store.createRecord('embedder', { id: 'asdf', embeddees: [first, second] });
  },
  
  model() {
    return this.store.peekAll('embedder').get('firstObject');
  }
});

serializers.embeddee.js

import RESTSerializer from 'ember-data/serializers/rest';

export default RESTSerializer.extend({});

serializers.embedder.js

import RESTSerializer from 'ember-data/serializers/rest';
import EmbeddedRecordsMixin from 'ember-data/mixins/embedded-records';

export default RESTSerializer.extend(EmbeddedRecordsMixin, {
  attrs: {
    embeddees: { serialize: 'records' }
  }
});

templates.application.hbs

Embeddee count: {{model.embeddees.length}}<br>
Serialized: <pre>{{serialized}}</pre>

twiddle.json

{
  "version": "0.8.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.5.1",
    "ember-data": "2.5.2",
    "ember-template-compiler": "2.5.1"
  }
}