Observers completed

controllers.about.js

import Ember from 'ember';

export default Ember.Controller.extend({
  observerCounter: 0,
  nameObserver: Ember.observer('model.firstName', 'model.lastName', function(){
    this.incrementProperty('observerCounter');
    console.log('observer counter: ', this.get('observerCounter'));
  }),
  computedCounter: 0,
  nameComputed: Ember.computed('model.firstName', 'model.lastName', function(){
    this.incrementProperty('computedCounter');
    console.log('computed counter: ', this.get('computedCounter'));
    return `${this.get('model.firstName')} ${this.get('model.lastName')}`;
  })
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Observer World',
});

controllers.index.js

import Ember from 'ember';

export default Ember.Controller.extend({
});

models.person.js

import Model from "ember-data/model";
import attr from "ember-data/attr";
import { belongsTo, hasMany } from "ember-data/relationships";

export default Model.extend({
  firstName: attr('string'),
  lastName: attr('string')
});

router.js

import Ember from 'ember';
import config from './config/environment';

const Router = Ember.Router.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('about');
});

export default Router;

routes.about.js

import Ember from 'ember';

export default Ember.Route.extend({
  model(){
    return this.store.peekAll('person').get('firstObject');
  }
});

routes.index.js

import Ember from 'ember';

export default Ember.Route.extend({
  init(){
    this.store.createRecord('person', { 
      firstName: 'Brandon', 
      lastName: 'Blaylock'
    })
  },
  model(){
    return this.store.peekAll('person').get('firstObject');
  }
});

templates.about.hbs

<h2>About</h2>
{{model.firstName}}
{{model.lastName}}
<br>
<br>
{{nameComputed}}

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
{{link-to 'Index' 'index'}}
{{link-to 'About' 'about'}}
<br>
<br>
{{outlet}}

templates.index.hbs

<h2>Index</h2>
<br>
First Name: {{input value=model.firstName}}
<br>
Last Name: {{input value=model.lastName}}

twiddle.json

{
  "version": "0.10.6",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.9.0",
    "ember-data": "2.9.0",
    "ember-template-compiler": "2.9.0",
    "ember-testing": "2.9.0"
  },
  "addons": {}
}