嵌套控制器中的Rails 6 Dup

class ParentController < ApplicationController
  def show
    @parent = Parent.find(params[:id])
    nested_show
  end

  private

  def nested_show
    # 尝试复制不可变对象
    @child = @parent.child.dup
  end
end

class ParentController < ApplicationController
  def show
    @parent = Parent.find(params[:id])
    nested_show
  end

  private

  def nested_show
    # 使用可变对象
    @child = @parent.child.dup if @parent.child.is_a?(String)
  end
end

class ParentController < ApplicationController
  def show
    @parent = Parent.find(params[:id])
    nested_show
  end

  private

  def nested_show
    # 深拷贝
    @child = Marshal.load(Marshal.dump(@parent.child))
  end
end