Ruby on rails Rails—POST请求数等于GET请求数

我正在尝试实现这个购物车应用程序，但出于某种原因，POST请求的数量似乎等于过去GET请求的总和。这会导致一些恼人的行为！ 我不明白为什么。。有人有主意吗

应用程序控制器：

 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

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

def index
  @products = Product.all
  @order_item = OrderItem.new
end

OrderItemsController：

 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

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

def index
  @products = Product.all
  @order_item = OrderItem.new
end

产品控制器：

 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

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

def index
  @products = Product.all
  @order_item = OrderItem.new
end

产品指数：

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

=>部分产品行：

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

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问题到底是什么？问题是发送了太多的POST请求。例如，当我按Add to Cart时，产品添加次数过多。。