Dragon

controllers.application.js

import Ember from 'ember';

const {
  get,
  set,
  isPresent
} = Ember;

export default Ember.Controller.extend({
  appName: 'Dragon',
  
  actions: {
    test() {
      let credentials = [
        {
          options: [
            { value: 'Boom' }
          ]
        }
      ];

      this.set('credentials', Em.ArrayProxy.create({
        content: credentials
      }));

      let firstCredentialOption = isPresent(credentials) && get(credentials, 'firstObject.options.firstObject');
      if (firstCredentialOption) {
        set(this, 'credentials.firstObject.value', get(firstCredentialOption, 'value'));
      }
    }
  }
});

templates.application.hbs

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

<button onclick={{action 'test'}}>Release the Dragon</button>

twiddle.json

{
  "version": "0.11.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.10.2",
    "ember-data": "2.11.0",
    "ember-template-compiler": "2.10.2",
    "ember-testing": "2.10.2"
  },
  "addons": {}
}