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

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.

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

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.

Here is how my models are related:

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

and:

class Item < ActiveRecord::Base
  belongs_to :estimates
end

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.

Thanks.

回答1:

??? 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 %>

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

来源：https://stackoverflow.com/questions/4936129/how-can-i-create-multiple-instances-of-an-assosiated-model-from-a-rails-3-form-f

标签

ruby-on-rails-3