Rails - Number of POST request equals number of GET requests -

i'm trying make shopping cart app happen, reason seems number of post request equals sum of past requests. results in quite annoying behaviour! can't figure out why.. have idea?

applicationcontroller:

 before_filter :current_delivery  def current_delivery    if session[:delivery_id]       @delivery = delivery.find(session[:delivery_id])    else       @delivery = delivery.create       session[:delivery_id] = @delivery.id    end        end 

orderitemscontroller:

def create  @delivery.order_items.new(order_item_params)  @delivery.save end 

productscontroller:

def index   @products = product.all   @order_item = orderitem.new end 

products index:

<% @products.each |product| %>   <%= render "product_row", product: product %> <% end %> 

=> partial product_row:

  <%= form_for @order_item, remote: true |f| %>     <%= f.number_field :quantity, value: 1, class: "form-control", min: 1 %>     <%= f.hidden_field :product_id, value: product.id %>     <%= f.submit "add cart", class: "btn btn-primary" %>    <% end %>