Get route for base class of STI class in Rails

Question

Say I have a rails app with 3 models, Person, Place and Thing. Say the Thing uses single table inheritance, so there are FancyThing and ScaryThing subclasses. Then there are routes defined with map.resources :people, :places, :things. So there are no controllers for FancyThings and ScaryThings, the ThingsController handles either type.

Now say I need to have code that shows a list of anything has links to them. If I have this code in my view:

<% @items.each do |item| %>
  <%= link_to item.name, item %>
<% end %>

If item is a Person or a Place, this works fine, polymorphic_path takes care of generating the correct route. But if item is a FancyThing or a ScaryThing, this blows up, because it will try to use fancy_thing_path, which there is no route for. I want to somehow make it use thing_path. Ideally there would be a method on Thing and/or its subclasses that somehow indicates the subclasses should use the base class to generate the route. Is there an elegant solution to this?

Answer 1

This is an open ticket on rails development. See the ticket for suggestions on how to deal with it.

Answer 2

Try using

map.resources :things
map.resources :fancy_things, :controller => 'things'
map.resources :scary_things, :controller => 'things'

Answer 3

Don't have a correct answer, but at least I can deal with this problem using non-DRY code :

map.resources :things, :has_many => :stuffs map.resources :fancy_things, :controller => 'things', :has_many => :stuffs map.resources :scary_things, :controller => 'things', :has_many => :stuffs

Hope the issue will be soon corrected in edge, since I'd like to see fancy_things only manage by :things controller. Using these routes, you will end with urls like : /fancy_things/1 whereas you maybe want /things/1

Answer 4

This will do the trick:

<% @items.map {|i| if i.class < Thing then i.becomes(Thing) else i end}.each do |item| %>
  <%= link_to item.name, item %>
<% end %>

This uses the ActiveRecord function "becomes" to do an "up-cast" of all subclasses of Thing to the Thing base class.