使fields_for以多步形式正确显示部分

Question

我在这里描述的多步形式的第二部分中插入=f.fields_for :customer。如果它在表单的第一步（_voucher_partial.html.haml），它可以正常工作，但如果我将它移动到第二步，它将不会显示。任何人都可以告诉我为什么，以及如何解决？我不明白为什么他们会被Rails区别对待。

谢谢！

顺序

class Order < ActiveRecord::Base
  attr_accessible :customer_attributes, :customer_id, :format

  belongs_to :customer
  accepts_nested_attributes_for :customer
  attr_writer :current_step

  def steps
    %w[voucher recipient delivery confirmation]
  end

  def current_step
    @current_step || steps.first
  end

  def next_step
    self.current_step = steps[steps.index(current_step)+1]
  end

  def previous_step
    self.current_step = steps[steps.index(current_step)-1]
  end

  def first_step?
    current_step == steps.first
  end

  def last_step?
    current_step == steps.last
  end

OrdersController

  # GET /orders/new
  # GET /orders/new.json
  def new
    session[:order_params] ||= {}
    @order = Order.new(session[:order_params])
    @order.build_customer(session[:order_params])
    @order.current_step = session[:order_step]
  end

  # POST /orders
  # POST /orders.json
  def create
    session[:order_params].deep_merge!(params[:order]) if params[:order]
    @order = Order.new(session[:order_params])
    @order.current_step = session[:order_step]
    if params[:back_button]
      @order.previous_step
    elsif @order.last_step?
      @order.save
    else
      @order.next_step
    end
    session[:order_step] = @order.current_step

    if @order.new_record?
      render 'new'
    else
      session[:order_step] = session[:order_params] = nil
      flash[:notice] = "Order saved."
      redirect_to @order
    end
  end

订单/ new.html.haml

%h1 New order

= form_for(@order) do |f|
  - if @order.errors.any?
    #error_explanation
      %h2
        = pluralize(@order.errors.count, "error")
        prohibited this order from being saved:
      %ul
        - @order.errors.full_messages.each do |msg|
          %li= msg
  = render "#{@order.current_step}_step", :f => f 
  = f.submit "Continue"
  = f.submit "Back", :name => "back_button" unless @order.first_step?

= link_to 'Back', orders_path

_recipient_step.html.haml

%h3
  Customer details

=f.fields_for :customer do |builder|
  =builder.label :name
  =builder.text_field :name

  =builder.label :email
  =builder.text_field :email

%h3
  Recipient details

.field
  = f.label :recipient_name
  = f.text_field :recipient_name

Answer 1

你能尝试用这种方式渲染部分：

= render partial: "#{@order.current_step}_step", object: @order, locals: { :f => f }

顺便说一句，在您的创建操作中，您始终会创建一个新订单，但不会重建客户！