Rails 5.1 form_with三重嵌套子窗体(孙子？？)下级未继承属性且未保存的

# 数据模型
class Parent < ApplicationRecord
  has_many :children
  accepts_nested_attributes_for :children
end

class Child < ApplicationRecord
  belongs_to :parent
  has_many :grandchildren
  accepts_nested_attributes_for :grandchildren
end

class Grandchild < ApplicationRecord
  belongs_to :child
end

# 控制器
class ParentsController < ApplicationController
  def new
    @parent = Parent.new
    @parent.children.build
    @parent.children.each do |child|
      child.grandchildren.build
    end
  end

  def create
    @parent = Parent.new(parent_params)
    if @parent.save
      # 保存成功的处理逻辑
    else
      # 保存失败的处理逻辑
    end
  end

  private

  def parent_params
    params.require(:parent).permit(children_attributes: [:id, :name, grandchildren_attributes: [:id, :name]])
  end
end

# 视图
<%= form_with(model: @parent, local: true) do |form| %>
  <%= form.fields_for :children do |child_form| %>
    <%= child_form.text_field :name %>
    <%= child_form.fields_for :grandchildren do |grandchild_form| %>
      <%= grandchild_form.text_field :name %>
    <% end %>
  <% end %>
  <%= form.submit %>
<% end %>