How can I extend ActiveRecord from app/modules? - ruby-on-rails

Question

I have several different acts_as_... custom class methods I'd like to use in my app. I would like the code for those methods to be in files in the app/modules directory.
I have been unable to get this working.
For instance, I have a file: app/modules/acts_as_lockable
module ActsAsLockable
def acts_as_lockable
before_create :set_lock
include InstanceMethods
end
module InstanceMethods
protected
def set_lock
now = Time.now.to_s
self.lock = Digest::SHA1.hexdigest(now)
end
end
end
ActiveRecord::Base.extend ActsAsLockable
And in application.rb
config.autoload_paths += %W(#{config.root}/app/modules)
When I try to load up a model that calls acts_as_lockable I get the following error:
NameError: undefined local variable or
method `acts_as_lockable'
My guess is that I shouldn't be autoloading the modules folder because ActiveRecord has already been loaded when I extend it? Is there another way to do this? I would like to be able to alter the file during development without restarting my server but that's more of a want that a need.

Answer 1

I think you're thinking about this in the wrong way.
You are adding this module to the load path,
but it will only load if you either say;
require 'acts_as_lockable'
or
ActsAsLockable
I'd suggest you never really want to say either of these inside your code.
The correct paradigm you're looking for is an "initializer".
I suggest you create a file called "config/initializers/acts_as_lockable.rb"
In this file you can either include the whole code,
or just include a require 'acts_as_lockable'
Normally I keep things like this inside the libs directory
ensure lib is in the load path
** config/application.rb **
config.autoload_paths += %W(#{config.root}/lib)
** lib/acts_as_lockable.rb **
module ActsAsLockable
def acts_as_lockable
before_create :set_lock
include InstanceMethods
end
module InstanceMethods
protected
def set_lock
now = Time.now.to_s
self.lock = Digest::SHA1.hexdigest(now)
end
end
end
then in the initializer
** config/initializers/acts_as_lockable.rb **
require 'acts_as_lockable'
ActiveRecord::Base.extend ActsAsLockable

Answer 2

The problem is that ruby autoload mechanism is a lazy process: When a constant like ActsAsLockable is used within your code, it looks for a file called acts_as_lockable.rb within the autoload_paths. As You never actually use ActsAsLockable, the file never gets loaded. You could do (although not tremendously beautiful):
ActsAsLockable
class MyModel < ActiveRecord::Base
acts_as_lockable
...
end
I think the acts_as_* pattern is ment to be used be plugins and gems to easily integrate functionality into your code. Plugins and gems are supposed to be in a final state when you integrate them into your project so you would not need the reloading functionality for the development mode.
I hope this helps.