formtastic - subset of values in accepts_nested_attributes_for - ruby-on-rails

Question

I have a model:
class Contact < ActiveRecord::Base
has_many :phones
accepts_nested_attributes_for :phones
end
I want to build 50 phone #s that users can add (there may already be phones 1 or 5, but I always want 50 available)
In my controller:
while contact.phones.length < 50
contact.phones.build({:phone_type_id => PhoneType['a_cool_type'].id})
end
In my view, I want to have 2 columns of phone #s 25 rows each
<%= semantic_form_for contact do |form| %>
<table width=50%>
<%= form.inputs :for => :phones[0..25] do |phone_form| %>
<td align="center"><%= phone_form.input :number, :label => false %></td>
....
<% end %>
</table>
<table width=50%>
<%= form.inputs :for => :phones[25..49] do |phone_form| %>
<td align="center"><%= phone_form.input :number, :label => false %></td>
....
<% end %>
</table>
<%end %>
Obviously the line:
<%= form.inputs :for => :phones[25..49] do |phone_form| %>
doesn't work, but it conveys my intention ( I hope). I want to have more control over how formtastic grabs the underlying object association.
The following works, but I can't do two columns easily without fancy css.
<%= form.inputs :for => :phones do |phone_form| %>
Any suggestions?
---------- Update ----
I was able to get around this in a roundabout way:
I built up a separate list of phone #s not as contact.phones.build, but Phone.new(:contact_id => contact.id) and store those in a list called #new_phones
Then my form looks like this:
<%= semantic_form_for #contact, :url => ..., do |f| %>
<% #new_phones[0...25].each_with_index do |phone, i| %>
<%= f.fields_for :phones, phone, :child_index => i do |phone_form| %>
<%= render "phone_fields", {:phone_form => phone_form, :phone => phone} %>
<%end%>
<% end %>
....
<% #new_phones[25...50].each_with_index do |phone, i| %>
<%= f.fields_for :phones, phone, :child_index => i+25 do |phone_form| %>
<%= render "phone_fields", {:phone_form => phone_form, :phone => phone} %>
<%end%>
<% end %>
<%end%>
This allowed me to display 25 phones on one part of the page, and 25 on another, with nested_attributes_for :phones working as expected on form submit.

Answer 1

I've always had problems with getting nested attributes working as I want but this may help resolve your issue.
Model:
class Contact < ActiveRecord::Base
has_many :phones
accepts_nested_attributes_for :phones
end
Controller:
See we're looping #contract.phones.build 50 times, this creates 50 new instances.
class Contact < ApplicationController
def new
#contact = Contact.new
25.times do
#contact.phones.build
end
end
end
View new.html.erb :
...
<%= p.semantic_fields_for :phones do |ec| %>
<%= ec.input :number %>
<% end %>
...
I did try a few attempts to intercept the loop, sadly with no definite clean avail.