How to require modules in Rails

Question

I have rails app with a module called http_helpers that lives in app/lib/modules/ and I want to use the methods in the module in my controllers. I was thinking of requiring the module in application_controller.rb so that the module's methods will be accessible to every controller.

application_controller.rb

class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception
  require "http_helpers"
end

However I'm getting an error:

LoadError (cannot load such file -- http_helpers):

I'm new to dealing with this side of rails (or ruby for that matter) and would very much appreciate some suggestions.

Thanks in advance!

score 2 · Answer 1 · edited May 23 '17 at 10:29

2

You use Module#include/extend modules, not files in Rails, because every file (at least those under app directory are preloaded).

So

class ApplicationController < ActionController::Base
  include HttpHelpers
  protect_from_forgery with: :exception
end

edit

Unless you're on Rails 5+, you need to add the folder to the autoload paths:

#config/application.rb:
config.autoload_paths << Rails.root.join('app', 'lib', 'modules')

edited May 23 '17 at 10:29

Community

1
1

answered Feb 27 '17 at 19:01

Andrey Deineko

51,333
10
112
145

That's because Rails pre-loads everything – Richard Peck Feb 27 '17 at 19:01
Okay but now I'm getting this error: `ActionController::RoutingError (uninitialized constant ApplicationController::HttpHelpers):` – Mark Feb 27 '17 at 19:06
@Mark maybe because you do not have a file called `http_helpers` with module called `HttpHelpers`? ;) Naming is crucial in Rails, because it is a base for lot's of magic behind it – Andrey Deineko Feb 27 '17 at 19:07
my module is: `module HttpHelpers` and the filename is: `http_helpers.rb` – Mark Feb 27 '17 at 19:08
@Mark is it under `app/helpers` directory? Also, if you name it `ApplicationHelper` you won't even need to `include` it, because Rails is smart enough to include modules from `helpers` directory into the corresponding (by name) controllers – Andrey Deineko Feb 27 '17 at 19:10
No, I mentioned in my post that the module is in `app/lib/modules/` and I'd like to keep it there if possible – Mark Feb 27 '17 at 19:11
You need to add the lib dir to the preload paths – Richard Peck Feb 27 '17 at 20:01
1

@RichardPeck the `lib` dir is under `app`, so I doubt it is the case – Andrey Deineko Feb 27 '17 at 20:01
@RichardPeck or is it only Rails 5 preloads everything from under `app`?.. – Andrey Deineko Feb 27 '17 at 20:02
1

I believe it's only Rails 5 which preloads all the /app folder – Richard Peck Feb 27 '17 at 20:32
1

I fixed it by removing the modules directory and simply putting the module in `app/lib`, but why can't rails seem to locate the module if its another layer deep? – Mark Feb 27 '17 at 20:37
@Mark to be honest I can't tell... Anyway, if the answer satisfies you - make sure to accept it, unless you're waiting for more to come. – Andrey Deineko Feb 27 '17 at 20:40
I think it might be a recursion issue – Richard Peck Feb 27 '17 at 20:44

score 1 · Answer 2 · answered Feb 27 '17 at 20:41

If you're using Rails 5+ (you have not specified), you can now include helpers directly in the controller using the helpers method:

class ApplicationController < ActionController::Base
  def index
    helpers.your_http_method
  end
end

If your module has specific helpers, you should convert it into an engine and then put the helpers into the app/helpers folder of your engine. We do this with a framework we use in our production apps:

This will allow you to call the helpers in your controllers without polluting your app's structure.

--

The trick is to make the engine a gem and put it in vendor/gems - this way you can reference it in the Gemfile as follows:

#Gemfile
gem "your_engine", path: "vendor/gems/your_gem"

If you decide to extract the functionality into an engine (you should), the setup would be as follows:

# app/vendor/gems/your_engine/lib/engine.rb
module YourEngine
  class Engine < Rails::Engine
    isolate_namespace YourEngine
  end
end

# app/vendor/gems/your_engine/app/helpers/your_engine/http_helpers.rb
class YourEngine::HTTPHelpers
  ....
end

How to require modules in Rails

application_controller.rb

2 Answers2

edit