如何在rails 5中使用form_for实现可选的嵌套表单

class User < ApplicationRecord
  has_many :addresses
  accepts_nested_attributes_for :addresses, allow_destroy: true
end

class Address < ApplicationRecord
  belongs_to :user
end

<%= form_for @user do |f| %>
  <%= f.label :name %>
  <%= f.text_field :name %>

  <%= f.fields_for :addresses do |address_fields| %>
    <%= address_fields.label :street %>
    <%= address_fields.text_field :street %>

    <%= address_fields.label :city %>
    <%= address_fields.text_field :city %>
  <% end %>

  <%= f.submit %>
<% end %>

class UsersController < ApplicationController
  def new
    @user = User.new
    @user.addresses.build
  end

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

  def edit
    @user = User.find(params[:id])
    @user.addresses.build if @user.addresses.empty?
  end

  def update
    @user = User.find(params[:id])
    if @user.update(user_params)
      # 更新成功的处理逻辑
    else
      # 更新失败的处理逻辑
    end
  end

  private

  def user_params
    params.require(:user).permit(:name, addresses_attributes: [:id, :street, :city, :_destroy])
  end
end