Rails 3以单一形式编辑多个记录

# 在模型中定义关联关系
class Order < ApplicationRecord
  has_many :order_items
  accepts_nested_attributes_for :order_items
end

# 在控制器中初始化多个记录
class OrdersController < ApplicationController
  def edit
    @order = Order.find(params[:id])
    @order.order_items.build
    @order.order_items.build
    @order.order_items.build
  end

  def update
    @order = Order.find(params[:id])
    if @order.update(order_params)
      redirect_to @order, notice: 'Order was successfully updated.'
    else
      render :edit
    end
  end

  private

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

# 在视图中使用fields_for方法生成多个记录的表单字段
<%= form_for @order do |f| %>
  <%= f.fields_for :order_items do |item_fields| %>
    <%= item_fields.text_field :name %>
    <%= item_fields.number_field :quantity %>
  <% end %>
  <%= f.submit 'Update' %>
<% end %>