Revert some changes of 20adce8a4e2d32548e7d7016dace250dd3e2eb9b

app/controllers/order_articles_controller.rb

@@ -18,7 +18,7 @@ class OrderArticlesController < ApplicationController
     if @order_article and @order_article.units_to_order == 0
       @order_article.units_to_order = 1 # FIXME: this is ugly if used in the receive form
     else
-      @order_article = OrderArticle.new(params[:order_article])
+      @order_article = @order.order_articles.build(params[:order_article])
     end
     @order_article.save!
   rescue

app/views/order_articles/_new.html.haml

@@ -1,5 +1,4 @@
 = simple_form_for [@order, @order_article], remote: true do |form|
-  = form.association :order, as: :hidden
   .modal-header
     = link_to t('ui.marks.close').html_safe, '#', class: 'close', data: {dismiss: 'modal'}
     %h3= t '.title'