当我不知道要添加多少个时，如何从 rails 3 form_for 创建关联模型的多个实例? [英] How can I create multiple instances of an assosiated model from a rails 3 form_for when I don't know how many I'm going to add?

问题描述

我有一个 form_for 来创建一个新的估计"，并且这些估计中的每一个都可以有无限数量的项目"(这就像一个零件号，但它会有自己的一组属性).在提交创建新估算的表单之前，我希望能够创建尽可能多的关联项目模型的实例，然后让它创建与该估算相关的所有关联项目.

I have a form_for that creates a new 'Estimate' and each of these estimates can have an unlimited number of 'Items' (this is like a part number, but it will have it's own set of attributes). I would like to be able to create as many instances of the associated Items model as I want to before I submit the form that creates the new Estimate, and then have it create all of the associated Items that go with that Estimate.

我在 form_for 和 accepts_nested_attributes_for 上的 API 中阅读了很多内容，我在谷歌上进行了广泛的搜索，并观看了有关嵌套模型表单的 railscasts，并且我已经阅读了我的 rails 3 书，但我已经尚未找到一种轨道方式"以从相同的形式一次性创建所有这些新对象.在 Railscast 中，Ryan 在控制器中有这样的东西:

I've read a lot in the API on form_for and accepts_nested_attributes_for, I've googled extensively, and I've watched the railscasts about nested model forms, and I've read through my rails 3 book, but I've yet to find a 'rails way' to create all of these new objects in one go from the same form. In the railscast, Ryan has something like this in the controller:

def new  
  @estimate = Estimate.new  
  3.times { @estimate.items.build }  
end

但是，我不知道每个估算将包含多少项.我也不确定我应该在视图中使用哪个 fields_for 语法，但我知道我可能必须使用 JavaScript 来动态创建新的表单字段.

However, I do not know how many items are going to be on each estimate. I'm also not sure which fields_for syntax I should be using in the view, but I do understand I'll probably have to use JavaScript to dynamically create new form fields.

以下是我的模型的关联方式:

Here is how my models are related:

class Estimate < ActiveRecord::Base
  has_many :items
  accepts_nested_attributes_for :items
end

和:

class Item < ActiveRecord::Base
  belongs_to :estimates
end

那么，有什么想法吗?就像我说的，我可以让我的应用执行此操作(我可能会使用大量 AJAX)，但我希望有人可能有更漂亮的解决方案.

So, any ideas? Like I said, I can make my app do this (I'll probably use a lot of AJAX), but I was hoping someone might have a prettier solution.

谢谢.

推荐答案

???你的方式是最好的 Rails 方式.也许您不知道为项目构建表单?通过 Rails 指南或 Rails API，您可以编写以下内容:

??? your way is the best Rails Way. Perhaps you don't know to build a form for items? By Rails Guides or Rails API's, you can write following:

<%= form_for @estimate do |f| %>
  <p>
    <%= f.label :xxx %>
    <%= f.text_field :xxx %>
  </p>
  <%= f.fields_for :items do |item_field| %>
    <p>
      <%= item_field.label :yyy %>
      <%= item_field.text_field :yyy %>
    </p>
  <% end %>
<% end %>

而且你可以使用非常好的 Gem，'nested_form'.请参阅:https://github.com/ryanb/nested_form

And you can use the sooooo good Gem, 'nested_form'. see: https://github.com/ryanb/nested_form

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