Namespacing Controllers & nesting Resources

Is it a terrible idea to use both Name-spacing and nested resources?

I want to have an admin area, with a bunch of controllers in them. Some resources in that area would make sense to be nested for example:

resources :suppliers do
  resources :products   
  resources :locations
end

Whilst namespacing like this:

 map.namespace :admin do |admin|
  resources :suppliers do
    resources :products 
    resources :locations
  end
 end

Is it possible / a good idea to use nesting within a namespace like this? How should i structure things?

Namespacing an admin area is a good idea as it keeps those controllers separated from your public/user facing controllers. The big win here is security since your admin actions are likely to be capable of doing more and may bypass certain security restrictions like removing or limiting the amount of authorization, depending on how you want to structure your administration access.

As for nesting resources, use it if it makes sense. If you never want to access one of the nested resources outside of the context of it's parent resource, then using nested resources is a good option.

As an example, if your admin interface was to be accessed by suppliers, and each admin was to be scoped to their resources only, then it might make authorization simpler to nest the resources since you can simply query through that nested resource and your authorization is simplified to checking that their account is tied to that supplier.

class Admin::ProductsController < AdminController
  before_filter :load_supplier

  # your actions

  def load_supplier
    # Will trigger a 404 if the supplier does not belong to the admin
    @supplier = current_admin.suppliers.find(params[:supplier_id])
  end
end

Of course it really depends on what your trying to accomplish, what is the expected audience of the admin area, will they have full access to everything. If so will they need access to resources outside of the context of any relationships. For example what if I'm an admin and I need to do some search/sort/filter on all of the products, regardless of the supplier (or maybe filtering by one or more suppliers), and then generate CSV/Excel from those constraints. In this case using nested resources might make this difficult or impossible.

I've personally found that nested resources make more sense in user/public facing controllers and to be more annoying in admin areas, but then I've always built admin interfaces that were limited to few people. In which case I typically turn to a gem like ActiveAdmin which basically gives you a full CRUD on each model with plenty of customization options.