New Twiddle

models.account.js

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

export default Model.extend({
  user: belongsTo(),
  balance: attr('number')
});

models.user.js

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

export default Model.extend({
  accounts: hasMany(),
  name: attr('string')
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    this.store.pushPayload({
      data: {
        type: "users",
        id: 1,
        attributes: {
          name: 'Alex'
        }
      }
    });
    
     this.store.pushPayload({
      data: {
        type: "accounts",
        id: 1,
        relationships: {
          user: {
            data: {
              id: '1',
              type: 'users'
            }
          }
        },
        attributes: {
          balance: 123
        }
      }
    });

    return this.store.peekRecord('user', 1);
  }
});

templates.application.hbs

<h1>Name: {{model.name}}</h1>

<h2>Accounts: {{model.accounts.length}}</h2>
<dl>
  {{#each model.accounts as |account|}}
    <dt>ID: {{account.id}}</dt>
    <dd>balance: {{account.balance}}</dd>
    {{account.user}}
  {{/each}}
</dl>

twiddle.json

{
  "version": "0.9.2",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.16.2",
    "ember-data": "2.16.4",
    "ember-template-compiler": "2.16.2"
  }
}