tap/app/views/order_products/_order_product.html.erb

<div class="col-md-3 form_products">
  <div class="thumbnail ">
    <div class="form_row center">
      <%= image_tag product.avatar %>
      <div class="caption">
        <h3><%= product.name %> - <%= content_tag :span, euro(product.price) %></h3>
        <p>
          <div class="input-group">
            <%= render 'btn_dec' %>
            <%= f.text_field :count, class: 'form-control row_counter', value: 0 %>
            <%= render 'btn_inc' %>

            <%= f.fields_for :product do |product| %>
              <%= product.hidden_field :price, class: :price %>
              <%= product.hidden_field :stock, class: :stock %>
            <% end %>
          </div>
        </p>
      </div>
    </div>
  </div>
</div>