send_file Rails3, Ruby 1.9.2

I'm perty new to rails and I have an app where I want to have secure
file downloads, so I can't just drop the files in public/data, I need
to use send_file. I found the post (pasted at bottom) that explained
how to do this. When I go to implement it, I wanted to try the
simplest thing first, so I have this code:

datafiles_controller.rb:
  def download
    send_file('/file_uploads/Productivity.pdf', :disposition
=> :attachment)
  end
datafiles/index.html.erb
            <%=button_to "Download File", :action=>'download'%>

when I load index.html it gives the error "No route matches
{:action=>"download", :controller=>"datafiles"}"
so even though "resources :datafiles" is already in my routes.rb file,
I added: get "datafiles/download"
now the page loads, I click the "Download File" button and it gives me
the error "No route matches "/datafiles/download""

I vaguely remember reading that every def in a controller should
correspond to it's own erb file, so I created Views/datafiles/
download.erb as a blank page.
But that didn't make any difference. I'm at a loss as to what I'm
doing wrong, can someone give me some suggestions?

post refered to above:

resources :datafiles will create some default routes, but they don't include download. You need to add a member route for the download action.

http://www.engineyard.com/blog/2010/the-lowdown-on-routes-in-rails-3/
http://guides.rubyonrails.org/routing.html

Luke

If I comment out everything in my index action in my
datafiles_controller
and paste in:
send_file('/file_uploads/Productivity.pdf', :disposition
=> :attachment)
it works, so obviously, the send_file command is good, the
problem is with my routing. What do I need to add to my
routes.rb file so I can create a new download action? or perhaps
even more generally does someone know of a good guide that
explains routing? I thought having "resources :datafiles" in my
routes.rb file was enough and rails would just detect any new
actions automatically.

excellent, ty

Are you going to make me do this for you ? :wink:

resources :datafiles do
  member do
    get :download
  end
end

And seriously, read this stuff:
http://www.engineyard.com/blog/2010/the-lowdown-on-routes-in-rails-3/
http://guides.rubyonrails.org/routing.html

Luke

in case someone else has similar problems, the code that I got working
is:

downloading: