Rails Against The Machine

First up custom finders/counters

has_many :photos,:class_name => 'Picture',
:finder_sql => '
SELECT pictures.*,
FROM pictures
WHERE pictures.code = \'#{code}\'
ORDER BY pictures.order,
:counter_sql => 'SELECT COUNT(*)
FROM pictures
WHERE pictures.code = \'#{code}\'

Three things which might trip you up
(1) counter_sql may need to be specified if your select is complex since by default it replaces the select caluse of the finder_sql with a simple count.
(2)use single quotes
(3)#{code} are active record attributes corresponding to column names you cannot use method names here

Now adding methods to the association

in your class where you declare has_many :pictures

class User < ActiveRecord::Base

has_many :pictures do

def custom_function
foo
end

private
def foo
self << 'foo'
end
end
end

so now you can do something like

p=User.new
p.pictures.custom_function