swaps the foreign key and primary key to fix has_many and has_one through belongs_to in Rails 2.3.x

patch_through_belongs_to.rb

class ActiveRecord::Associations::ClassMethods::JoinDependency::JoinAssociation
  
  # has_many and has_one through belongs_to are broken becuase the order of the primary key
  # and foreign table key need to be reversed.  this detects and fixes it.
  def association_join_with_through_belongs_to_fix
    join = association_join_without_through_belongs_to_fix
    if [:has_many, :has_one].include?(reflection.macro) && reflection.options[:through] && source_reflection.macro == :belongs_to
      connection        = reflection.active_record.connection
      parent_table_name = connection.quote_table_name(parent.aliased_table_name)
      parent_key        = connection.quote_column_name(parent.primary_key)
      join_table_name   = connection.quote_table_name(aliased_join_table_name)
      jt_foreign_key    = through_reflection.options[:as] ? through_reflection.options[:as].to_s + '_id' : through_reflection.primary_key_name
      join_key          = connection.quote_column_name(jt_foreign_key)
      
      # if this is a belongs to we need to swap the order in which the keys are used
      join = join.gsub(/(#{parent_table_name}\.)#{parent_key}/, "\\1#{join_key}").gsub(/(#{join_table_name}\.)#{join_key}/, "\\1#{parent_key}")
    end
    join
  end
  alias_method_chain :association_join, :through_belongs_to_fix
  
end