Dangerous oneWays

components.todo-display.js

import Ember from 'ember';

const { computed, set } = Ember;

export default Ember.Component.extend({
  todo: null,
  title: computed.oneWay('todo.title'),
  body: computed.oneWay('todo.body'),

  actions: {
    updateBody(){
      set(this, 'body', 'jk, do this thing. haha! youre stuck doing this thing instead');
    }
  }
});

controllers.application.js

import Ember from 'ember';

const { set } = Ember;

export default Ember.Controller.extend({
  todos: null,
  selectedTodo: null,

  actions: {
    pageTodo(todo) {
      set(this, 'selectedTodo', todo);
    }
  }
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    return [
      { title: 'Todo A', body: 'Do Thing A'},
      { title: 'Todo B', body: 'Do Thing B'},
      { title: 'Todo C', body: 'Do Thing C'},
    ]
  },

  setupController(controller, model) {
    controller.setProperties({
      todos: model
    })
  }
}); 

styles.app.css

.todos {
  margin: 75px;
  text-align: center;
}

.selected-todo {
  border: 1px solid black;
  padding: 25px;
  height: 150px;
}

.todo__content {
  padding-bottom: 25px;
}

templates.application.hbs

<div class="todos">
  <div class="selected-todo">
    {{#if selectedTodo}}
      {{todo-display todo=selectedTodo}}
    {{else}}
      <div>Please View A Todo.</div>
    {{/if}}
  </div>
  <br>
  <div>
    {{#each todos as |todo|}}
      <button {{action "pageTodo" todo}}>
      	View {{todo.title}}
      </button>
    {{/each}}
  </div>
</div>

templates.components.todo-display.hbs

<div class="todo">
  <div class="todo__content">
    <h3>{{title}}</h3>
    <div>{{body}}</div>
  </div>
  <button {{action "updateBody"}}> Update body </button>
</div>

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}