New Twiddle

adapters.application.js

import DS from 'ember-data';

export default DS.JSONAPIAdapter.extend({
  findRecord() {
    return {
      data: {
        id: '1',
        type: 'books',
        attributes: {
          config: {} 
        }
      }
    }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  actions: {
    foo() {
      this.model.set('config.foo', 2);
      console.log(this.model.get('config'));
      console.log(this.model.changedAttributes()); 
    }
  }
});

models.book.js

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

export default Model.extend({
  config: attr()
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    return this.store.findRecord('book', 1);
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<button onclick={{action "foo"}}>Change</button>
<br>
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}