tap/app/views/order_items/_order_item.html.erb

<div class="col-md-3 form_products">
  <div class="thumbnail ">
    <div class="form_row center">
      <div class="form_row_image">
        <%= image_tag product.avatar %>
      </div>
      <div class="caption">
        <%= content_tag :h4, "#{product.name} (#{euro(product.price)})" %>
        <%= f.counter :count, skip_label: true, wrapper_class: "input-group", class: "row_counter" %>
        <%= f.fields_for :product do |product| %>
          <%= product.hidden_field :price_cents, class: :price %>
          <%= product.hidden_field :stock, class: :stock %>
        <% end %>
      </div>
    </div>
  </div>
</div>