Can I have url_for use a prefix option in Ruby on Rails?

In a project I am working on, Apache is set up to only forward requests that come in as /prefix/* to mongrel. How can I tell ruby on rails to generate all URLs with that prefix?

I have the routes set up for forward to the correct controller action by doing this:

map.connect 'sfc/:controller/:action'

but that doesn't seem to affect the way that the url writer generates the URLs.

Any ideas?

From stackoverflow Kyle Boon

• The RAILS_RELATIVE_URL_ROOT environment variable should do the trick, though I haven't tried it myself.

  From Can Berk Güder

• What about using the :path_prefix option:

  map.connect ':controller/:action', :path_prefix => 'sfc'
  

  From Mike Breen

• You probably have another route (probably one of the default routes at the bottom of routes.rb) that URL generation is using in preference to the sfc-prefixed match. For example, if you have

  map.connect "sfc/:controller/:action"
  map.connect ":controller/:action/:id"
  

  then url_for(:controller => 'x', :action => 'y', :id => 3) will return "/x/y/3". If you change it to

  map.connect "sfc/:controller/:action"
  map.connect "sfc/:controller/:action/:id"
  

  you should get "/sfc/x/y/3".

  From Matt Burke

• Mongrel accepts a --prefix option that will then be prepended to all generated URLs. This is the only way I know of to be able to run multiple instances of the same application on one server.

  Corban Brook : Rails 2.3+ changes broke the --prefix option in mongrel and it has not been updated. You will have to monkey patch the code yourself to get it to work properly.
  From Kyle Boon