Why doesn't composite stone work for Rails?

Question

I followed the instructions here by setting the compos_primary_keys gem through

sudo gem install composite_primary_keys

This worked fine. Now when I add the following to my model

set_primary_keys :user_id, :group_id

and i get

undefined method `set_primary_keys' for #<Class:0x1043bfe20>

In addition, the use of multiple primary keys during migration, as described here , is not affected.

Any ideas why this might not work and how to make it work?

Note. I do not want to talk about why I should not use composite keys - I have already decided and just want it to work. Thank!

Answer 1

require 'composite_primary_keys' environment.rb, ?