ActiveRecord :include not working for belongs_to with foreign_key

Question

I have a two models set up like this:

class User < ActiveRecord::Base
  # external_id column in database
end

class UserUpload < ActiveRecord::Base
  belongs_to :user, :primary_key => "external_id", :foreign_key => "external_user_id"
end

However, whenever I do

upload = UserUpload.find(id, :include => :user)

The sql that gets emitted is always looking for ID (and using zeros):

select * from users where id in (0,0,0,0 ... 0,0)

Am I doing something wrong, or is there a problem using foreign_keys in a belongs_to relationship with include?

Answer 1

I have just ran into this same problem. There's a patch that applies to Rails 2.3.5 on bug #3208 but it hasn't been applied to the 2-3-stable branch yet.

I have created a monkey patch for this bug as it is causing performance issues in my app. Place fix_belongs_to_include_with_primary_key.rb in your config/inititalizers directory and restart your app to apply it.