New Twiddle

controllers.application\.js

import Controller from '@ember/controller';
import { inject as service } from '@ember/service';
import { get, set } from '@ember/object';

export default class ApplicationController extends Controller {
  @service store;
  appName = 'Ember Twiddlez';

	constructor() {
    super(...arguments);
   
    const barRecord = this.store.createRecord('bar', {name: 'barRecord'})
    
    //set(barRecord, 'id', 'adsas')
    const fooRecord = this.store.createRecord('foo', {
      bar: barRecord
    })
    
    this.fooRecord = fooRecord
  }
}

models.bar\.js

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

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

export default class extends Model {
  @belongsTo('foo') foo;
  @attr('string') name;
}

models.foo\.js

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

export default class extends Model {
  @belongsTo('bar') bar;
}

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
name: {{this.fooRecord.bar.name}}
id: {{this.fooRecord.bar.id}}
<br>
<br>
{{outlet}}

<br>
<br>

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0",
    "ember-data": "3.18.0"
  }
}