r.js

import Ember from 'ember';

export default Ember.Route.extend({
  'currentOrder': Ember.inject.service(),
  model(){
    return Ember.Object.create({
      // in the template: (subclass of Ember.ArrayProxy) == :)
      'invoices': this.get('store').findAll('invoice'),
      // in the template: [object Object] == :(
      'currentOrders': this.get('currentOrder').current()
    });
  }
});

s.js

import Ember from 'ember';

export default Ember.Service.extend({
  currentUser: Ember.inject.service(),
  store: Ember.inject.service(),
  orderBasket: Ember.inject.service(),
  order: function(){
    return this.get('currentUser').user()
      .then(user => user.get('orders'))
      .then(orders => orders.get('firstObject'));
  },
  past(){
    return this._orders_for('past');
  },
  current(){
    return this._orders_for('current');
  },
  addOption(option, quantity){
    return this.order().then((order) => this.get('orderBasket').add(order, option, quantity));
    
  },

  _orders_for(type){
    return this
      .get('currentUser')
      .user()
      .then(user => this._filter(user, {type: type}));
  },

  _filter(user, by){
     return this
       .get('store')
       .query('order', {
           user_id: user.get('id'),
           filters: by
       });
  }
});