Question

I’m inheriting code which has:

class Graphic < ActiveRecord::Base
  has_many :comments, :foreign_key => 'asset_id',  
  :conditions => 'asset_type_id = 5', 
  :order => 'created_at', :dependent => :destroy

class Comment < ActiveRecord::Base
  belongs_to :graphic, :foreign_key => :asset_id

It seems to me like the has_many should not have the foreign_key (it’s referenced in the belongs_to ok I believe) but I am not sure, do you know?

i.e. should it be

class Graphic < ActiveRecord::Base
  has_many :comments,  
  :conditions => 'asset_type_id = 5', 
  :order => 'created_at', :dependent => :destroy

class Comment < ActiveRecord::Base
  belongs_to :graphic, :foreign_key => :asset_id

Answer 1

I think you are trying to do something that is already baked in Rails. You should use Polymorphic Associations here.

class Comment
  belongs_to :asset, :polymorphic => true
end

class Graphic
  has_many :comments, :as => :assets
end

This way, you need to declare foreign_key on neither side.