@each two levels deep is not supported

controllers.application.js

import Ember from 'ember';

function emberFruit(name, price, color) {
  let fruit = {
    name: name,
	  price: price,
    attrs: {color: color}
  };
  return Ember.Object.create(fruit);
}

export default Ember.Controller.extend({
  
  fruits: [
    emberFruit('grape', 4, 'purple'),
    emberFruit('watermelon', 6, 'yellow')
  ], 
  
  fruitNames: Ember.computed('fruits.[]', function() {
    console.log('fruits.[]');
    return this.get('fruits');
  }),
  
  fruitPrices: Ember.computed('[email protected]', function() {
    console.log('[email protected]');
    return this.get('fruits').map(function(fruit) {
      return fruit.price;
    });
  }),
  
  /* 
   * @each works only one level deep
   * 
   * It won't recompute when the color property changes.
   * (click `paint it black`)
   *
   * This computed will still trigger when elements
   * are added or removed in the fruits list.
   * (click `add apple`)
   *
   * Documentation:
   * https://guides.emberjs.com/v2.2.0/object-model/computed-properties-and-aggregate-data/
   *
   * Github issue:
   * Cannot observe changes to nested properties on array using @each
   * https://github.com/emberjs/ember.js/issues/541
   */
  fruitColors: Ember.computed('[email protected]', function() {
    console.log('[email protected]');
    return this.get('fruits').map(function(fruit) {
      return fruit.attrs.color;
    });
  }),
  
  fruitsAttrs: Ember.computed.mapBy('fruits', 'attrs'),

  fruitColors2: Ember.computed('[email protected]', function() {
    console.log('fruitColor2');
    return this.get('fruitsAttrs').map(function(attr) {
      return attr.color;
    });
  }),
  
  actions: {
    
    addApple: function() {
      let apple = emberFruit('apple', 2, 'red');
      this.get('fruits').addObject(apple);
    },
    
    upPrices: function() {
      let fruits = this.get('fruits');
      fruits.forEach(function(fruit) {
        let p = fruit.get('price');
        fruit.set('price', p + 1);
      });
    },
    
    paintItBlack: function() {
      let fruits = this.get('fruits');
      fruits.forEach(function(fruit) {
        fruit.set('attrs.color', 'black');
      });
    }
    
  }
  
});

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

.table {
  display: flex;
  flex-direction: row;
}

.col {
  margin: 2px;
}

templates.application.hbs

<h1>@each two levels deep is not supported</h1>

<p>
  Note how the third column doesn't update after clicking <b>change color for all</b>.
</p>

<div class="table">
<div class="col">
  name
	<hr>
	{{#each fruitNames as |fruit|}}
  	{{fruit.name}}
  	<br>
	{{/each}}
</div>

<div class="col">
	prices
	<hr>
	{{#each fruitPrices as |price|}}
  	{{price}}
  	<br>
	{{/each}}
</div>

<div class="col">
	@each nested prop
	<hr>
	{{#each fruitColors as |color|}}
	  {{color}}
	  <br>
	{{/each}}
</div>

<div class="col">
	fruitColors2
	<hr>
	{{#each fruitColors2 as |color|}}
	  {{color}}
	  <br>
	{{/each}}
</div>

</div>

<br><br>

<button {{action "addApple"}}>add apple</button>
<button {{action "upPrices"}}>prices up</button>
<button {{action "paintItBlack"}}>change color for all</button>

<br><br>

<!-- Of course the underlying list is always updated with each button click. -->

fruits list raw:
<br><br>
{{#each fruits as |fruit|}}
	{{fruit.name}} {{fruit.price}} {{fruit.attrs.color}}
	<br>
{{/each}}
  
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.10.4",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.2.2",
    "ember-data": "2.7.0",
    "ember-template-compiler": "2.2.2"
  },
  "addons": {}
}