checkbox-all-valid-items

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  defaultAllChecked: false,
  allValidItems: Ember.computed.oneWay( 'defaultAllChecked' ),
  
  isAllChecked: Ember.computed('allValidItems', 'items.[]', function() {
    return this.get('allValidItems.length') === this.get('items.length');
  })
});

controllers.application.js

console.clear();
import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  allValidItems: Ember.computed('collection.@each.isValid', function() {
    return this.get( 'collection' ).filter(function(item) {
      return item.get( 'isValid' );
    });
  }),
  
  collection: Em.A([
  	Em.Object.create({ name: 'foo', isValid: true }),
    Em.Object.create({ name: 'bar', isValid: false }),
    Em.Object.create({ name: 'baz', isValid: true })
  ])
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{my-component items=collection allValidItems=allValidItems}}

templates.components.my-component.hbs

<ul>
	{{#each items as |item|}}
		<li>{{ item.name }} {{input type="checkbox" checked=item.isValid}}</li>
	{{/each}}
</ul>

<p>All Checked Items: {{ isAllChecked }}</p>

twiddle.json

{
  "version": "0.10.7",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.10.0",
    "ember-data": "2.10.0",
    "ember-template-compiler": "2.10.0",
    "ember-testing": "2.10.0"
  },
  "addons": {}
}