How To Namespace Controllers In Rails

Namespacing controllers in a Ruby on Rails application is a great way to isolate different features: invoicing, authentication, etc. It’s also pretty simple to implement, so there are no reasons not to do it if you need it.

The initial state

Let’s start with a sample controller named ProposalsController:

# app/controllers/proposals_controller.rb
class ProposalsController < ApplicationController

  def index
    # something cool is probably happening here
  end

end

This file currently lives in app/controllers/proposals_controller.rb, and the routes are:

# routes.rb
resources :proposals, only: [:index]

Moving things up

Now let’s say we want to move this controller into a module named Invoice. Here are the steps to follow to add a namespace.

1. Create the folder app/controllers/invoice

The first thing to do is create a new folder under app/controllers, named invoice.

2. Move the proposals_controller.rb file in the invoice folder

3. Add the namespace to the ProposalsController

This is done with the module keyword from Ruby that will encapsulate the ProposalsController class.

# app/controllers/invoice/proposals_controller.rb
module Invoice
  class ProposalsController < ApplicationController

    def index
      # something cool is probably happening here
    end

  end
end

4. Add a scope or a namespace in the routes

For the change to routes.rb, we have two options, depending on how we want the URI path to be affected.

With this first solution, the generated path in the browser will be /invoice/proposals, and it will use the controller located at app/controllers/invoice/proposals_controller.rb.

# routes.rb
namespace :invoice do
  resources :proposals, only: [:index]
end

This second solution will not add anything to the path. The proposals will be available at /proposals, and use the controller located at app/controllers/invoice/proposals_controller.rb.

# routes.rb
scope module: :invoice do
  resources :proposals, only: [:index]
end

The End

That’s it, let me know if you have any comments!