Uh Oh

application.controller.js

import Ember from 'ember';
const { computed } = Ember;

export default Ember.Controller.extend({
  items: [{
    name: 'Foo',
    state: {
      isActive: true
    }
  }, {
    name: 'Bar',
    state: {
      isActive: true
    }
  }, {
    name: 'Baz',
    state: {
      isActive: true
    }
  }],
  
  activeItems: computed('items.@each.state.isActive', function() {
   	return this.get('items').filter(item => item.state.isActive); 
  })
});

application.template.hbs

<p><code>items</code></p>
<ul>
  {{#each items as |item|}}
  	<li>
    	{{item.name}}
      {{input type="checkbox" checked=item.state.isActive}}
    </li>
  {{/each}}
</ul>
<p><code>activeItems: computed.filterBy('items', 'state.isActive')</code></p>
<ul>
  {{#each activeItems as |item|}}
    <li>{{item.name}}</li>
  {{/each}}
</ul>

twiddle.json

{
  "version": "0.5.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.2.0/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.2.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.2.0/ember-template-compiler.js"
  }
}