Generate multiple XML files based on database

Can someone provide an example of using Builder to create mul开发者_开发知识库tiple XML files from a SQL database. I can easily create one containing the entire database as in here...

def index
  respond_to do |format|
   format.xml { @rides = Rides.find(:all) }
  end
end

This will create a file called index.xml based on a file I created called index.xml.builder which contains the following code

xml.instruct!
xml.rides do
@rides.each do |ride|
  xml.item("togive" => ride.togive, "totake" => ride.totake, "howlong" => ride.howlong,       "isoffer" => ride.isoffer, "id" => ride.id, "contact" => ride.contact)
 end
end

Here are the only lines in my routes.rb

map.resources :rides
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format'

This works fine, but how would I create a new file that contains the last element in Rides?

Thanks

edit: changed from format.rss to format.xml

I'm not entirely sure what you're trying to achieve, but you could have another method in your controller that returns the last ride:

def last
  respond_to do |format| 
    format.xml { @last_ride = Rides.last } 
  end 
end 

And then in the view template last.xml.builder you could have something like:

xml.instruct! 
xml.rides do 
  xml.item("togive" => @last_ride.togive, "totake" => @last_ride.totake etc...) 
end

If you went with this approach then you'd need to modify your config/routes.rb file to add a new collection route for the list action:

map.resources :rides, :collection => { :last => :get }

• This would then let you access the route using http://localhost:3000/rides/last.xml

Alternatively you could simply make the find call within the controller's index method conditional so that it fetches all rides or the last ride as appropriate. In this case you should be able to re-use the existing index.xml.builder view template because it will just output a collection that happens to only ever contain one ride.