Question

I’m having a really strange issue with named helpers. So let’s start off with the routes in question:

  resources :subjects, path: 'library' do
    resources :modules, controller: 'subject_modules'
  end

Where Subjects#to_param returns self.slug. Now, for a subject named “Foo” and module with id 1, where the subject is @subject and module is m:

• link_to subject_modules_path(@subject, m) gives /library/foo/modules.1
• link_to edit_subject_module_path(@subject, m) gives /library/foo/modules/1/edit
• link_to m gives /library/1/modules/physics

As for link_to [@subject, m], I get:

Routing Error

No route matches {:action=>"show", :controller=>"subject_modules", :subject_id=>#<Subject id: 2, name: "Foo", created_at: "2011-12-30 02:00:38", updated_at: "2011-12-30 02:00:38", slug: "foo">, :id=>#<SubjectModule ---snipped--->}

Does anyone know why the routes are broken the way they are, and what I could possibly do to fix this?

EDIT:

Rake routes:

    subject_modules GET    /library/:subject_id/modules(.:format)          {:action=>"index", :controller=>"subject_modules"}
                    POST   /library/:subject_id/modules(.:format)          {:action=>"create", :controller=>"subject_modules"}
 new_subject_module GET    /library/:subject_id/modules/new(.:format)      {:action=>"new", :controller=>"subject_modules"}
edit_subject_module GET    /library/:subject_id/modules/:id/edit(.:format) {:action=>"edit", :controller=>"subject_modules"}
     subject_module GET    /library/:subject_id/modules/:id(.:format)      {:action=>"show", :controller=>"subject_modules"}
                    PUT    /library/:subject_id/modules/:id(.:format)      {:action=>"update", :controller=>"subject_modules"}
                    DELETE /library/:subject_id/modules/:id(.:format)      {:action=>"destroy", :controller=>"subject_modules"}

Answer 1

There appears to be some quirk in Rails’ routing system currently.

Using subject_module_path(@subject, m) initially caused a “can’t find route” error for me (which I tried at the time I wrote the question), but it somehow worked eventually.

I can’t pinpoint this issue so unfortunately I have no idea of its cause. This problem happened with Rails 3.1.3.