New Twiddle

adapters.customer.js

import DS from 'ember-data';
import Ember from 'ember';

export default DS.JSONAPIAdapter.extend({
  findAll(store, type, sinceToken, snapshotRecordArray) {
    console.log('find all customers...');
    return Ember.RSVP.resolve({
      data: [{
        id: '1',
        type: 'customer',
        attributes: { name: 'customer-one'},
      },{
        id: '2',
        type: 'customer',
        attributes: { name: 'customer-two'},
      }]
    });
  }
});

adapters.product.js

import DS from 'ember-data';
import Ember from 'ember';

export default DS.JSONAPIAdapter.extend({
  findRecord (store, type, id, snapshot)  {
    console.log('find product ', id);
    return Ember.RSVP.resolve({
      data: {
        id: '2',
        type: 'product',
        attributes: { name: 'product-one'},
        relationships: {
          customer: {
            data: { type: 'customer', id: '1' },
            links: {
              related: '/customers/1'
            }
          }
        }
      }
    });
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

models.customer.js

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

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

models.product.js

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

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

routes.index.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    return Ember.RSVP.hash({
        customers: this.store.findAll('customer'),
        product: this.store.find('product', 1),
    }).then(h => h.product);
  }
});

templates.application.hbs

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

templates.index.hbs

<dl>
	<dt>Product</dt>
  <dd>{{model.id}} - {{model.name}}</dd>
  
  <dt>Products customer</dt>
  <dd>{{model.customer.id}} - {{model.customer.name}}</dd>
</dl>

twiddle.json

{
  "version": "0.8.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.5.1",
    "ember-data": "2.5.2",
    "ember-template-compiler": "2.5.1"
  }
}