Shallow nested route Ember Data adapter

application.js

import DS from 'ember-data';

export default DS.ActiveModelAdapter.extend({
  buildURL: function(type, id, record) {
    if (id) {
      return this._super.apply(this, arguments);
    }

    var parent = this.get('parent');
    var path = [];
    if (parent) {
      var parentType = record.constructor.typeForRelationship(parent).typeKey;
      var prefix = this.urlPrefix();
      var host = this.get('host');

      path.push(this.pathForType(parentType));
      path.push(record.get(parent + '.id'));
      path.push(this.pathForType(type));

      if (prefix) { path.unshift(prefix); }

      path = path.join('/');

      if (!host && path) { path = '/' + path; }

      return path;
    } else {
      return this._super.apply(this, arguments);
    }
  }
});