title: Ember.js: Load related multiple models
body: <p>Since the ember-guides explains how to load mutliple models on a route like that</p>
  
  <pre><code>export default Ember.Route.extend({
    model() {
      return Ember.RSVP.hash({
        songs: this.get('store').findAll('song'),
        albums: this.get('store').findAll('album')
      });
    }
  });
  </code></pre>
  
  <p>Im wondering how to load only the related model-entries from a second one, like loading ALL songs but only the albums which are indexed in the songs if we assume that the song model containing this</p>
  
  <pre><code>...
  albums: hasMany('album'),
  ...
  </code></pre>
  
  <p>How can I do that?</p>