Filtering results through URL (e.g. new?forum_id=3)

Is there a special code you have to place in the routes so filtering
results through the URL works?

For example, Ruby Forum does it with:

Any ideas?

Hi Bob,

It seems that the example you gave may be doing something different
that what you describe. I believe the forum_id will be used as a value
in a new topic form, not as a "filter" for a list of topics.

You might look at this:
Specifically the part about routing association.

If you wanted to "filter" a list of topics by forum_id you might do
something like the following:
# routes.rb
map.resources :forums do |forums|
  forums.resources :topics

This would generate routes like forum_topics and new_forum_topic so
you could call the following in your controllers & views:
# some_view.html.erb
<%= link_to "click here to see #{} topics",
forum_topics_path(@my_forum) %>

This would result in a link to /forums/7/topics where @my_forum's id
is 7.

For a complete list of routes you've defined try this in your command
$ rake routes

When GETing the path above, your topics_controller index action will
be called. In that method you'll need to look for params[:forum_id]
when finding your list of topics for the desired forum:
# topics_controller
def index
  if params[:forum_id]
    #find topics belonging to a specified forum
    @forum = Forum.find(params[:forum_id])
    @topics = @forum.topics
    # find all topics
    @topics = Topic.find(:all)

Good luck.

*untested code examples

Really appreciate the help, gsterndale! =)

Very detailed. Thank you so much!