Creating assocations

controller.js

// you have to have assocations defined and in view you can check isDirty 
// it is automatically pushed to your assocation (in our case order)

  actions: {
    addOrderProduct: function() {
      var order = this.get("controllers.order.model");
      var orderProduct = this.store.createRecord("orderProduct", {order: order});
      return orderProduct;
    }
  }

order-model.js

  orderProducts: DS.hasMany("orderProducts", {async: true}),

order-product-mode.js

order: DS.belongsTo("order", {async: true}),

order-route.js

// this file is automtically genereted, so you dont have to do it

model: function(params) {
  this.store.find("order", params.order_id)
}