including a module in my model rails 3

i have a function that i wanna use in different models and i wanna do it DRY.
so my best option as i see it is to include a module i made (that is in the lib/ directory) in the model.
my code basicly looks something like this (for testing purpose, i didn’t implement my function yet)

lib/model_helper.rb
module ModelHelper
def bla
puts “hello world”
end
end

app/models/test.rb
class Test < ActiveRecord::Base
include ModelHelper
end

now the weird part is, when i try to do this in rails 2.2 it works but when trying to do this in rails 3.0.0 it doesnt.

why is that?
is there any way of doing it in the newest version of rails?

It ought to work in both versions just the same. You may need to be more
specific what "not work" means. Also, it is relevant where that module
is located. Rails 1.x and 2.x automatically load files from lib, rails
3.x does not. So if your ModelHelper is in lib/model_helper.rb you need
to require that file explicitly where you use it.

If the module is tied to your application anyway, I'd put it in
app/models. In my opinion, app/models is not only for subclasses of
ActiveRecord::Base, rather, it is the place where the model layer of an
app resides.

Michael

the error i get is:

NameError: uninitialized constant Test::ModelHelper

I am having the same issue…

you need to require it in rails 3 or add "lib" directory to autoload
paths

Robert pankowecki