PostgreSQL, Rails and :order => problem

Question

I have the following line in my ActiveRecord model:

class Record < ActiveRecord::Base
    has_many :users, :through => :record_users, :uniq => true,         


        

Answer 1

I ran into something similar before and I believe it's an AR bug related to PGSQL (https://rails.lighthouseapp.com/projects/8994/tickets/1711-has-many-through-association-with-order-causes-a-sql-error-with-postgresql).

I got around it by dropping the DISTINCT (:uniq) directive and resolved the uniq records another way. Kind of a bummer though.

Answer 2

I suppose you could call it a bug in ActiveRecord. PosgreSQL is a bit more restrictive than MySQL. You can help out ActiveRecord by setting up the association like this instead:

class Record < ActiveRecord::Base
  has_many :users,
   :through => :record_users,
   :select => 'DISTINCT users.*, record_users.index',
   :order => "record_users.index ASC"

Answer 3

Just posted this issue on rails's issue tracker on github (copied from lighthouse ticket so we could bring it back.. it was marked invalid):

https://github.com/rails/rails/issues/520

Promote it if you want this fixed nicely! :)