Ember-data- HasMany Not triggering computed properties

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

models.calendar.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: DS.attr('string'),
    days: DS.hasMany('day'),
    dates: Ember.computed('days.@each', function () {
      console.log("dates computed in calendar model  ");
        return this.get('days').map(day => day.get('date'));
    })
});

models.day.js

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

export default Model.extend({
  date: DS.attr('string'),
    calendar: DS.belongsTo('calendar')
});

routes.application.js

import Ember from 'ember';
export default Ember.Route.extend({
  beforeModel(){
    this._super(...arguments);
    $.mockjax({
      url: '/calendars',
      type: 'GET',
      responseText:{
      "data": [{
        "type":"calendar",
        "id":1,
        "attributes": {
          "id":1,
          "name":"first calendar",
          "days":[2,3],
        },
        "relationships": {
          "days": {
            "data":[
              {"id":2,"type":"day"},
              {"id":3,"type":"day"}
            ]
          }
        }
      },
              {
          "type":"day",
        	"id":2,
        	"attributes":{
          	"id":2,
          	"calendar":1,
          	"date":"2016-06-15"
        	}	
        },
               {
        "type":"day",
        "id":3,
        "attributes":{
          "id":3,
          "calendar":1,
          "date":"2016-06-17"
        }
      }]
    }
    });
    $.mockjax({
      url: '/red',
      type: 'GET',
      responseText:{'one':1}
    });
    $.mockjax({
      url: '/days',
      type: 'GET',
      responseText:{
        "data":[{
          "type":"day",
        	"id":2,
        	"attributes":{
          	"id":2,
          	"calendar":1,
          	"date":"2016-06-15"
        	}	
        },
               {
        "type":"day",
        "id":3,
        "attributes":{
          "id":3,
          "calendar":1,
          "date":"2016-06-17"
        }
      }]
      }
    });  
  },
  model(){    
    return  this.store.findAll('calendar');
  },
  afterModel(resolvedModel,transition){
    this._super(...arguments); 
    console.log("resolvedmodel");
    console.log(resolvedModel);
  },
  setupController(){
  this._super(...arguments);
    console.log('setupcontroller');    
	}
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
Calendar 
{{#each model as |cal|}}
 Name: {{cal.name}} <br>
 {{#each cal.days as |singleday|}}
  id:{{singleday.id}} cal: {{singleday.calendar}} date : {{singleday.date}}
  <br>
 {{/each}}
 
 
 <br>
The "regular" property
<ul>
{{#each cal.days as |d|}}
    <li>{{d.date}}</li>
{{/each}}
</ul>

The computed property
<ul>
{{#each cal.dates as |d|}}
    <li>{{d}}</li>
{{/each}}
</ul>
 
{{/each}}



<br>
{{outlet}}
<br>
<br>

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",
    "jquery-mockjax":"https://cdnjs.cloudflare.com/ajax/libs/jquery-mockjax/1.6.2/jquery.mockjax.min.js",
    "ember": "2.5.1",
    "ember-data": "2.5.2",
    "ember-template-compiler": "2.5.1"
  }
}