Rails Ruby on Rails → 2.x

Let's say we have this model: class Client < ActiveRecord::Base has_and_belongs_to_many :pools, :class_name => 'Pool', :foreign_key => 'client_id',

                      :finder_sql => %q{SELECT * FROM "pools" INNER JOIN "clients_pools" ON "pools".id = "clients_pools".pool_id WHERE ("clients_pools".client_id = #{self.clients_pools_client_id})},
                      :delete_sql => %q{DELETE FROM "clients_pools" WHERE client_id = #{self.clients_pools_client_id} AND pool_id = #{self.record.id}},
                      :insert_sql =>%q{INSERT INTO "clients_pools" ("client_id", "pool_id") VALUES (#{self.clients_pools_client_id}, #{record.id})}

protected # if clinet kind is other that base use parent_id def clients_pools_client_id

if self.kind_id != 1
  self.parent_id
else
  self.id
end

end end

In rails 2.2 when we will try to this: Client.first.pools

Sql will be generated from this method construct_sql: activerecord-2.2.0/lib/active_record/associations/has_and_belongs_to_many_association.rb

But when we will do preload Client.find(:first, :include => :pools).pools AR will try firstly to do preload, ommiting finder_sql and generating it from relection, execute it with [] result then it will again do construct_sql but now without any execution.

from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/associations/has_and_belongs_to_many_association.rb:80:in `construct_sql'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/associations/association_collection.rb:21:in `initialize'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/associations.rb:1289:in `new'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/associations.rb:1289:in `pools'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:180:in `send'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:180:in `preload_has_and_belongs_to_many_association'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:180:in `each'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:180:in `preload_has_and_belongs_to_many_association'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:120:in `send'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:120:in `preload_one_association'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:114:in `each'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:114:in `preload_one_association'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:91:in `preload_associations'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:90:in `preload_associations'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:90:in `each'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/association_preload.rb:90:in `preload_associations'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/base.rb:1492:in `find_every'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/base.rb:1452:in `find_initial'
from /Library/Ruby/Gems/1.8/gems/activerecord-2.2.0/lib/active_record/base.rb:587:in `find'

It seems that something here is really bad. If we have :finder_sql preload shouldn't generate it own sql. It should just do :finders_sql.

I thnik preload_has_and_belongs_to_many_association should ignore preload of :pools and just execute :finder_sql query and return it as array. Just like we have it in has_many.