CODEWITHSUNDEEP
ruby-on-rails-3
shigeya
shigeya

Reputation: 4922

How I can organize namespace of classes in app/modules with rails?

[This is a follow-up question to "How I can modularize Rails model?"]

Is there anyway to organize classes in app/models directory of Rails? Do I have to use single top-level namespace for all of the classes?

Initial motivation is, I want place business logic classes which do not inherited from ActiveRecord::Base into app/models directory. Searching this site reveals many answers which recommend to place business logics classes in the app/models directory. I posted a different question, and got recommendation that it is possible to place such classes into lib directory.

Now I'm curious. I'd like to place these classes into different namespace and directory in apps/models directory which recommended by others. Is it possible?

Actually, I experiment that, but it seems to me that is what rails is not expected. If I create such a class (like SomeModName::ClassInMod in some_mod_name/class_in_mod.rb ) it does not get loaded. Also, I defined constants inside the module. Since they're not loaded, I can't use them. Actually, with rspec it work without problem, but with rails server, the class does not loaded. I'm sure it is related to autoloading issue.

In addition to the classes mentioned above, classes inherited from ActiveRecord::Base can be placed into some namespaces inside a module. I'm curious whether this work well or not too.

So the question in other words: can I make rails happy by configuring these files to be loaded, or is not the way rails designed?

Upvotes: 3

Views: 5553

Answers (1)

Arsen7
Arsen7

Reputation: 12840

Yes, you can define an ActiveRecord class in a module. The easy way is to use the generator:

./script/rails generate model logic/phase_logic
./script/rails generate model logic/evaluation_logic

Observe, that Rails will create additionally a file with the definition of the module. In this case:

# app/models/logic.rb
module Logic
  ...
end

# app/models/logic/phase_logics.rb
class Logic::PhaseLogic < ActiveRecord::Base
  ...
end

# app/models/logic/evaluation_logics.rb
class Logic::EvaluationLogic < ActiveRecord::Base
  ...
end

Your problems with constants defined in the module were caused by the fact, that you defined the constants in the definition module "wrapped" around only one model, from the two you have created. A very important part in understanding ruby (and Rails) - especially for people who have strong background in compiled languages - is to remember that there is no compilation phase, so the definition of some class is read and executed only when that specific class is used. Sometimes a week after the application server has been started and served thousands of requests.

Thus, as I said in the previous question's answer, the problem with autoloading was that sometimes the definition of the constants was read after the definition which was trying to use them. The order was random - if the first used object happened to be EvaluationLogic, then the error emerged. It the first object happened to be PhaseLogic, everything was fine.

Now, when you have a file for the module itself, and define constants in that file (app/models/logic.rb), autoloading will be able to find and execute the definitions before any class starts to use them. I hope everything will be OK.

Upvotes: 6

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