Devise in namespaces

courses_controller.rb

class Api::V1::CoursesController < ApplicationController

  def create
    current_user ## is nil even though there's a user logged in. How do I access current_user?
  end

end

routes.rb

  namespace "api" do
    namespace "v1" do
      resources :users
      resources :courses do
        resources :units
      end
      resources :contents
      resources :units do
        resources :units
      end
    end
  end


  devise_for :users do
    get 'users/sign_out' => 'devise/sessions#destroy'
    post 'users' => 'devise/registrations#create'
  end