New Twiddle

controllers.application.js

import Ember from 'ember';
import { isEmpty } from '@ember/utils';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  actions: {
    async validate(changeset){
      isEmpty(changeset);
    } 
  }
});

models.box.js

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

export default Model.extend({
  size: attr('string')
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  model(){
  	return this.store.createRecord('box', { size: 'one' });
  }
});

templates.application.hbs

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

{{#with (changeset model) as |box|}}
  {{input type="text" value=box.size}}
  
  <button {{action 'validate' box}}>Validate</button>
{{/with}}
<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",
    "ember-changeset": "2.0.0"
  }
}