StackOverFlow-32855039

application.controller.js

import Ember from 'ember';

// model is in the route

export default Ember.Controller.extend( {

  actions: {
  	showCover(book) {
      book.set('coverVisible', true);
      console.log(book.coverVisible);
    }
  }

});

// route = 'this' > model > books > book > coverVisible

application.route.js

import Ember from 'ember';

var bookData = [
  {
    name: "Book1",
    thing: 'all at the same time :(',
    coverVisible: false
  },
  {
    name: "Book2",
    thing: 'all at the same time :(',
    coverVisible: false
  },
  {
    name: "Book3",
    thing: 'all at the same time :(',
    coverVisible: false
  }
];

export default Ember.Route.extend({
  
  model() {
    return bookData;
  }
  
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>

<ul>
  {{#each model as |book|}}
      <li> {{book.name}} - 

      {{#if book.coverVisible}}
      	{{book.thing}}
      {{/if}}

			{{#unless book.coverVisible}}
      <button {{action "showCover" book}}>
      	Show Cover
      </button>
      {{/unless}}

      </li>
  {{/each}}
</ul>

models.book.js

import DS from 'ember-data';

var type = function(input) {
  return DS.attr(input);
};

export default DS.Model.extend({
  name:           type('string'),
  thing:        	type('string'),
  readingReview:  type('boolean')
});

twiddle.json

{
  "version": "0.4.11",
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.9/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/1.13.11/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.9/ember-template-compiler.js"
  }
}