title: Rails named routes for the show action
body: <p>In my app I assign a url's <code>href</code> attribute as <code>profile_path</code> when using <code>resources :profiles</code> in my routes.rb file. I do not pass any id into <code>profile_path</code> yet the app somehow correctly assumes that it is the profile of the <code>current_user</code>. How does rails know this? Is this simply a default that rails assumes if you don't pass in an id?</p>