title: Static nested resource params name on Rails routes
body: <p>I'm playing on Rails routing but I can't figure out how to manage this. The problem is at <code>user_posts(1)</code> and <code>user(4)</code> routes, the params have different names - <code>id</code> and <code>user_id</code></p>
  
  <p>What I'm trying to achieve is a static param name for the same resource.</p>
  
  <p>I have this route file</p>
  
  <pre><code>Rails.application.routes.draw do
    shallow do
      resources :users, module: :users, only: [:index, :show] do
        resources :posts, module: :posts, only: [:index, :show]
      end
    end
  end
  </code></pre>
  
  <p>The routes generated are</p>
  
  <pre><code>   user_posts(1) GET  /users/:user_id/posts(.:format)      users/posts/posts#index
     post(2) GET        /posts/:id(.:format)                 users/posts/posts#show
     users(3) GET       /users(.:format)                     users/users#index
     user(4) GET        /users/:id(.:format)                 users/users#show
  </code></pre>
  
  <p>I tried <code>resources :user param: :user</code> but the generated route at <code>user_posts</code> is <code>/users/:user_user_id/posts</code></p>
  
  <p>Is possible to achieve a <code>:user_id</code> param and <code>:post_id</code> param for every route using <code>resources</code>?</p>