Q:

Best practices: Namespace or resources for admin interface dashboard Mongoid

I will build a admin interface for my aplication back-end. 
I am using Mongoid, and I want to know What is the best for make my own Backend Interface. 
I can not use active_admin because it does not works for mongoid odm. 
I have in my routes:
devise_for :admins
namespace :admin do
 resources :categories
 resources: users
 resources: posts
 . 
 . 
 . 
end

I have in my controller categories for example:
class Admin::CategoriesController < ApplicationController
  before_filter :authenticate_admin!    # assuming you're using devise
   def index
    #etc. 
  end
end

Its better use namespace or resources?   
which is best practice to create an interface for the administrator with others odms or database without using gems as active_admin, rails_admin, typus...etc

A:

Use namespace but remember this:
Do not use the same word as namespace and resources
namespace :admin
  resources :categories
end

is fine as long as you don't have a model resource named admin or admins.  Otherwise, you will have a hard time debugging or constructing the proper routes( admin_foo_bar_path, can refer either admin namespace or admin resource, which confuses both you and rails ).