Why does 'extend ActiveSupport::Concern' cause `undefined method 'recycle!'`?

Working on Rails Engine.

I want to make the controllers customizable whereever the Rails Engine is used.

Therefore, I was trying to use extend ActiveSupport::Concern on the Engine controller class and include it in MyRailsApp.

https://gist.github.com/4185823

# code in my rails engine

moduel MyEngine

class SomeController

extend ActiveSupport::Concern

def engine_some_method

end

end

end

# code in my rails app where engine is implemented

class SomeController

include MyEngine::SomeController

def app_some_method

end

# code that's available by including the Rails Engine code

# def engine_some_method

# end

end

But, this breaks my rpsec controller tests because of an undefined "recycle" method.

12) Qe::Admin::QuestionPagesController POST reorder

Failure/Error: xhr :post, :create,

NoMethodError:

undefined method `recycle!' for #<Qe::Admin::QuestionPagesController:0x007f80aa1c7528>

# ./spec/controllers/admin/pages_controller_spec.rb:69:in `block (2 levels) in <top (required)>'

When I comment out the "include MyEngine::Controller" everything passes.

Why?

But, this breaks my rpsec controller tests because of an undefined
"recycle" method.

12) Qe::Admin::QuestionPagesController POST reorder
Failure/Error: xhr :post, :create,
NoMethodError:
undefined method `recycle!' for
#<Qe::Admin::QuestionPagesController:0x007f80aa1c7528>
# ./spec/controllers/admin/pages_controller_spec.rb:69:in `block (2
levels) in <top (required)>'

When I comment out the "include MyEngine::Controller" everything passes.

If it's commenting out the include that fixes things, why are you so
sure that it's the extend at fault rather than something else in the
module? Personally I'd be inclined to thing that by including your
module you're accidentally shadowing an existing method on the
controller - if you were to show a minimal example that reproduces the
problem rather than dummy code someone might be able to have a guess
(I suspect the issue may have been lost in translation from your
actual code to the example you gave since the latter isn't valid ruby
(for example you're including a class rather than a module)

Fred

What you said makes sense.

I incorrectly said I commented out

include MyEngine::SomeController

when I meant to say commenting out

extend ActiveSupport::Concern

fixes the issue.

The codeabse is here, https://github.com/twinge/questionnaire_engine/tree/8836c2a3b92e676ead4653d11696eb182b63746e.

The specific Controller Class is here, https://github.com/twinge/questionnaire_engine/blob/8836c2a3b92e676ead4653d11696eb182b63746e/app/controllers/qe/admin/elements_controller.rb

The specific Controller Spec test is here, https://github.com/twinge/questionnaire_engine/blob/8836c2a3b92e676ead4653d11696eb182b63746e/spec/controllers/admin/elements_controller_spec.rb

What you said makes sense.

I incorrectly said I commented out
include MyEngine::SomeController

when I meant to say commenting out
extend ActiveSupport::Concern

Calling extend activesupport::concern on a controller sounds like a
weird thing to do
- it's supposed to be used on modules. What were you trying to do
with it?

Fred

> What you said makes sense.

> I incorrectly said I commented out
> include MyEngine::SomeController

> when I meant to say commenting out
> extend ActiveSupport::Concern

Calling extend activesupport::concern on a controller sounds like a
weird thing to do
- it's supposed to be used on modules. What were you trying to do
with it?

And I assume that the reason this causes a problem is something to do
with how as::concern changes the behaviour of include so as to setup
module dependencies.

Fred

I think I need to wrap class methods in a “module ClassMethods” block.

require 'active_support/concern'

module M
  extend ActiveSupport::Concern

  included do
    scope :disabled, where(:disabled => true  )
end

  module ClassMethods
    ...
  end
end

I think I need to wrap class methods in a “module ClassMethods” block.

Yes, that’s the way to add class methods with AS::Concern.

Fred