I currently have a routes.rb file that looks like this:

map.resources :profiles do |profile|
  profile.resources :projects, :has_many => :tasks
end

And this gives me routes like this:

/profiles/:profile_id/projects/:project_id/tasks

This is close to what I want, but instead of the '/profiles/:profile_id/' section I want to just have a username in place of that so the route would look something like:

/:profile_user/projects/:project_id/tasks

How can I achieve something like this? I have looked all over and haven't found anything about how to do this, but I also might not have been searching for the right thing.