Rails 4.1: Creating routes by calling method in controller - ruby-on-rails

Question

I want to create a method that, when called from a controller, will add a nested resource route with a given name that routes to a specific controller. For instance, this...
class Api::V1::FooController < ApplicationController
has_users_route
end
...should be equivalent to...
namespace :api do
namespace :v1 do
resources :foo do
resources :users, controller: 'api_security'
end
end
end
...which would allow them to browse to /api/v1/foo/:foo_id/users and would send requests to the ApiSecurityController. Or would it go to Api::V1::ApiSecurityController? It frankly doesn't matter since they're all in the same namespace. I want to do it this way because I want to avoid having dozens of lines of this:
resources :foo do
resources :users, controller: 'api_security'
end
resources :bar do
resources :users, controller: 'api_security'
end
Using a method is easier to setup and maintain.
I'm fine as far as knowing what to do once the request gets to the controller, but it's the automatic creation of routes that I'm a little unsure of. What's the best way of handling this? The closest I've been able to find is a lot of discussion about engines but that doesn't feel appropriate because this isn't separate functionality that I want to add to my app, it's just dynamic routes that add on to existing resources.
Advice is appreciated!

Answer 1

I ended up building on the blog post suggested by #juanpastas, http://codeconnoisseur.org/ramblings/creating-dynamic-routes-at-runtime-in-rails-4, and tailoring it to my needs. Calling a method from the controllers ended up being a bad way to handle it. I wrote about the whole thing in my blog at http://blog.subvertallmedia.com/2014/10/08/dynamically-adding-nested-resource-routes-in-rails/ but the TL;DR:
# First draft, "just-make-it-work" code
# app/controllers/concerns/user_authorization.rb
module UserAuthorization
extend ActiveSupport::Concern
module ClassMethods
def register_new_resource(controller_name)
AppName::Application.routes.draw do
puts "Adding #{controller_name}"
namespace :api do
namespace :v1 do
resources controller_name.to_sym do
resources :users, controller: 'user_security', param: :given_id
end
end
end
end
end
end
end
# application_controller.rb
include UserAuthorization
# in routes.rb
['resource1', 'resource2', 'resource3'].each { |resource| ApplicationController.register_new_resource(resource) }
# app/controllers/api/v1/user_security_controller.rb
class Api::V1::UserSecurityController < ApplicationController
before_action :authenticate_user!
before_action :target_id
def index
end
def show
end
private
attr_reader :root_resource
def target_id
# to get around `params[:mystery_resource_id_name]`
#target_id ||= get_target_id
end
def get_target_id
#root_resource = request.fullpath.split('/')[3].singularize
params["#{root_resource}_id".to_sym]
end
def target_model
#target_model ||= root_resource.capitalize.constantize
end
def given_id
params[:given_id]
end
end