Ember can't get data from hasMany relationship - ember.js

Question

I try to build Rails+Ember app using Ember data.
Model:
export default DS.Model.extend({
name: DS.attr('string'),
content: DS.attr('string'),
image_before: DS.attr('string'),
created_at: DS.attr('date'),
updated_at: DS.attr('date'),
status: DS.attr('number'),
comments: DS.hasMany('comment', {async: true}),
user: DS.belongsTo('user'),
});
and get json like this (json is generated with active_model_serializers)
{"work":{
"id":3,
"user_id":1,
"content":"My first photo",
"image_before": "image_before/original/AnViWyuup5I.png",
"created_at":"2015-08-11T16:57:24.153Z",
"updated_at":"2015-11-13T11:39:44.076Z",
"status":1,
"comment_ids":[13]
},
"comments": [{
"id": 13,
"text": "good!",
"created_at": "2015-09-28T10:34:16.461Z",
"user_id": 2
}]
}
Template is:
<div class="work__img-wrapper">
<img class="work__img" src="{{model.image_before}}">
</div>
<div class="work__content">{{model.content}}</div>
<div class="work__comments-list">
<strong>Comments( {{model.comments.length}} ):</strong>
{{#each model.comments as |comment|}}
<div class="work__comment">
<div class="work__comment-text">{{comment.text}}</div>
</div>
{{/each}}
</div>
At page, I get all information about work and Comments( 0 ), but Ember Inspector at Chrome shows comment.
How i can print comments too?

Answer 1

Your model definition should read:
comments: DS.hasMany('comment', {async: false}),
because the related data is being side-loaded with the response, not being fetched asynchronously.
If this is an Ember 2.0 application, the default async setting is true. From the Ember Blog (http://emberjs.com/blog/2015/06/18/ember-data-1-13-released.html, emphasis mine):
In Ember Data 2.0 relationships will be asynchronous by default. Sync
relationships will still be supported but you will need to manually
opt into them by setting { async: false } on your relationships. Ember
Data 1.13 will log a deprecation warning you if you have any
relationships where the async property is not explicitly set.
Additionally you can use ember-watson to help identify cases in your
codebase where you have relationships without an explicit async
property.

Answer 2

Problem solved. By default, DS.hasMany associated IDs are not added to the objects that are serialized (http://emberjs.com/api/data/classes/DS.EmbeddedRecordsMixin.html).
Should add
export default DS.ActiveModelSerializer
.extend(DS.EmbeddedRecordsMixin)
.extend({
attrs: {
comments: {serialize: 'ids', deserialize: 'ids'}
}
});