The Rails way to creating in-app links to non-trivial routes? - ruby-on-rails

Question

I've been digging through routing documentation and seem to have only uncovered half of the necessary info needed for this one.
If I create a route which looks like:
match 'attendances/new/:class_date/:student_id'
I'm afraid I'm completely unclear on how to create an appropriate link_to incantation which is capable of fulfilling the above.
For example, I seem to have no problems creating this URL:
http://localhost:3000/attendances/new?class_date=2012-05-07&student_id=5
but I've yet to find appropriate docs which explains how to create this:
http://localhost:3000/attendances/new/2012-05-07/5
Could someone provide a helpful example and/or a link to docs which discusses how to do this?
I realize that trying to use link_to might be completely inappropriate here. And I realize I could munge together some code which will craft the appropriate links, but I suspect that doing so will completely miss some better, Ruby-on-Rails way to doing this.
Edit: Corrected proposed match route, above.
Edit 2: Going on "mu is too short"'s suggestion, here's what my routes.rb now looks like:
NTA::Application.routes.draw do
resources :students
resources :libraries
resources :year_end_reviews
resources :notes
resources :ranktests
resources :attendances
match 'attendances/new/:class_date/:student_id', :as => :add_attendance
resources :ranks
get "home/index"
root :to => "home#index"
end
and here's the relevant view:
<% today = Date.today %>
<% first_of_month = today.beginning_of_month %>
<% last_of_month = today.end_of_month %>
<% date_a = first_of_month.step(last_of_month, 1).to_a %>
<h2><%= today.strftime("%B %Y") %></h2>
<table id="fixedcolDT">
<thead>
<tr>
<th>Name</th>
<% date_a.each do |d| %>
<th><%= d.day %></th>
<% end %>
</tr>
</thead>
<tbody>
<% #students.each do |s| %>
<tr>
<td><%= s.revfullname %></td>
<% date_a.each do |d| %>
<% student_attend_date = Attendance.find_by_student_id_and_class_date(s.id, d) %>
<% if student_attend_date.nil? %>
<td><%= link_to "--", add_attendance_path(d, s.id) %></td>
<% else %>
<td><%= student_attend_date.class_hours %></td>
<% end %>
<% end %>
</tr>
<% end %>
</tbody>
</table>
and here's what I get back after the initial reload (before trying to restart WEBrick):
ArgumentError
missing :controller
Rails.root: /Users/jim/Documents/rails/NTA.new
Application Trace | Framework Trace | Full Trace
config/routes.rb:15:in `block in <top (required)>'
config/routes.rb:1:in `<top (required)>'
This error occurred while loading the following files:
/Users/jim/Documents/rails/NTA.new/config/routes.rb
I'll pastebin what I got back after my failed attempt to restart WEBrick, if interested.

Answer 1

First of all, you want to give the route a name so that you'll get the appropriate helper methods:
match ':attendances/:new/:class_date/:student_id' => 'controller#method', :as => :route_name
That will generate two methods that you can use to build the URL:
route_name_path: The path for the URL, no scheme, hostname, ...
route_name_url: The full URL including scheme, hostname, ...
Those methods will use their parameters for the route's parameter values in order so you could say:
<%= link_to 'Pancakes!', route_name_path(att, status, date, id) %>
and :attendances would be att, :new would be status, etc. Alternatively, you could pass a Hash to the method and use the parameter names directly:
<%= link_to 'Pancakes!', route_name_url(
:attendances => att,
:new => status,
:class_date => date,
:student_id => id
) %>