Rails - 使用form_for和fields_for，如何在fields_for块中访问子对象？ [英] Rails - Using form_for and fields_for, how do you access the sub-object while in the fields_for block?

问题描述

在我的第一个rails应用程序中，我试图使用 form_for 和 fields_for 来创建一个嵌套的对象窗体。到目前为止这么好，但我不知道如何在 fields_for 块中访问子对象。我已预填充子对象中的一个字段，其中包含要显示在用户说明中的数据。

In my first rails app I'm trying to use form_for and fields_for to create a nested object form. So far so good, but I can't figure out how to access the sub-object while in the fields_for block. I've pre-populated a field in the sub-object with data that I want to show in the user instructions.

模型 >
Garage：

has_many :cars, :dependent => :destroy         
accepts_nested_attributes_for :cars

Car：

belongs_to :garage

车库管理员

def new
  @garage = Garage.new
  for i in 1..5 
    @garage.cars.build :stall_number => i
  end
end

_form.html.erb strong>

<%= form_for @garage do |f| %>
  <%= f.label :title, "Garage Name" %><br />
  <%= f.text_field :title %>
  <% f.fields_for :cars do |builder| %>
    <p>Enter license for car parked in stall: <%= car.stall_number %></p>
    <%= f.label :license, "License #:" %><br />
    <%= f.text_field :license %>
  <%= end %>
<%= end %>

正如您所看到的，在用于汽车的生成器块中，我想在我的用户中显示指令，字段： car.stall_number （在我的控制器中填充一个整数）：

As you can see, inside the builder block for :cars, I want to show, in my user instructions, the field: car.stall_number (populated in my controller with an integer):

<p>Enter license for car parked in stall: <%= car.stall_number%></p>

我尝试了许多不同的想法： @ car.stall_number ， object.car.stall_number 等。多次搜索并查看 fields_for 源代码并没有帮助我理解。我会很感激任何指导。

I've tried a many different ideas: @car.stall_number, object.car.stall_number, etc. No joy. Multiple searches and a look at the fields_for source code haven't helped my understanding. I would appreciate any guidance.

更新：为了澄清，根据Dan的建议，我试过 builder.stall_number 但它会导致$< / p>



Update: For clarification, per Dan's suggestion I have tried builder.stall_number but it results in a

NoMethodError: undefined method 'stall_number' for #<ActionView::Helpers::FormBuilder:0x00000102a1baf0>

推荐答案

我今天自己处理了这个问题。

I just dealt with this today myself.

您可以通过以下方式访问fields_for的对象：

You can access the object of the fields_for through:

builder.object

其中，构建器是您的fields_for表单构建器对象。在您的特定情况下，您可以说：

where builder is your fields_for form builder object. In your particular case, you can say:

<p>Enter license for car parked in stall: <%= builder.object.stall_number%></p>

这应该为你做！

这篇关于Rails - 使用form_for和fields_for，如何在fields_for块中访问子对象？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！