Save has-many associations

Rails
1

I have the following association

class Document < ActiveRecord::Base
has_many :sections
has_many :items, :through => :sections
end
class Section < ActiveRecord::Base
belongs_to :document
has_many :items
end
class Item < ActiveRecord::Base
belongs_to :section
end

Here is the sample view for the ‘new’ action
<% form_for(@document) do |f| %>
<%= f.error_messages %>

Header


<%= f.label :hdrcomment %> <%= f.text_field :hdrcomment %>

<% for section in @document.sections %> <% f.fields_for section, :index => section do |s| %> <%= section.seqnum %>
<% for item in section.items %> <% s.fields_for item, :index => item do |i| %> <%= i.text_area :comments %>
<% end %> <% end %> <% end %> <% end %>

<%= f.submit "Submit Document" %>

<% end %>

What is way to save the header, sections and items. Do I have to iterate
the request hash.
The below code doesn’t work. Gives ActiveRecord::UnknownAttributeError
inDocumentsController#create

def create
@document = Document.new(params[:document])
@document.save!
end

Request:
{“commit”=>“Submit Document”,
“authenticity_token”=>"+uOqJn1DSjzK6r1iIkaIqZa9VrKpU2Yr/A6zP0vg0eM=",
“document”=>{“section”=>{"#Section:0xb74045f4"=>{“item”=>{"#Item:0xb73d2860"=>{“comments”=>“asdf”},
“#Item:0xb73d1af0”=>{“comments”=>“sdf”}}},
“#Section:0xb7403794”=>{“item”=>{"#FeedbackItem:0xb73ce6fc"=>{“comments”=>“sdf”}}},
“#Section:0xb740ea90”=>{“item”=>{"#Item:0xb73e0e74"=>{“comments”=>“asd”}}}},
“hdrcomment”=>" asdf"}}

Thanks much.