computed-property-qp

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  items: [
    {key: 1, title: "ONE"},
    {key: 2, title: "TWO"},
    {key: 3, title: "THREE"}
  ],
  
  queryParams: ['active'],
  activeItem: Ember.computed('active', {
    get(k) { 
      console.log(this.get('active'), 'getter');
    	return this.get('items').findBy('key', this.get('active')); 
  	},
		set(k, value) {
      console.log(value, 'setter');
			this.set('active', value.key);
      return value;
		}    
  }),
  active:1,
                               
	actions: {
  	setItemObject(key) {
			let obj = this.get('items').findBy('key', key);
      this.set('activeItem', obj);
		}                             
  }
});

templates.application.hbs

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


active: {{active}}
<br>title: {{activeItem.title}}

<br><br>
<a href="" {{action 'setItemObject' 1}}>1</a> | 
<a href="" {{action 'setItemObject' 2}}>2</a> | 
<a href="" {{action 'setItemObject' 3}}>3</a>

twiddle.json

{
  "version": "0.15.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.2.2",
    "ember-template-compiler": "3.2.2",
    "ember-testing": "3.2.2"
  },
  "addons": {
  }
}