访问rails中的嵌套参数

class Order < ApplicationRecord
  has_many :order_items
  accepts_nested_attributes_for :order_items, allow_destroy: true
end

class OrderItem < ApplicationRecord
  belongs_to :order
end

class OrdersController < ApplicationController
  def new
    @order = Order.new
    @order.order_items.build # 初始化一个空的订单项以便在表单中添加
  end

  def create
    @order = Order.new(order_params)
    if @order.save
      redirect_to @order, notice: 'Order was successfully created.'
    else
      render :new
    end
  end

  private

  def order_params
    params.require(:order).permit(:customer_name, order_items_attributes: [:id, :product_name, :quantity, :_destroy])
  end
end

<%= form_with(model: @order, local: true) do |form| %>
  <%= form.label :customer_name %>
  <%= form.text_field :customer_name %>

  <%= form.fields_for :order_items do |item_form| %>
    <%= item_form.label :product_name %>
    <%= item_form.text_field :product_name %>

    <%= item_form.label :quantity %>
    <%= item_form.number_field :quantity %>

    <%= item_form.check_box :_destroy %>
    <%= item_form.label :_destroy, 'Remove this item' %>
  <% end %>

  <%= form.submit %>
<% end %>