Ruby / Rails - AJAX pagination of nested resources - How do I determine the parent resource?

My model has Posts, Users, and Comments. Users can leave Comments on/about Posts. Every Comment belongs to a User and a Post. Therefore, the Comment model has a user_id field and a post_id field.

When viewing a Post, I want to paginate through that Post's comments.

When viewing a User, I want to paginate through that User's comments.

I want to paginate using AJAX (via the Kaminari gem).

I have my nested routes set up for both.

On the Post, the URL being hit is http://localhost:3000/posts/{:id}/comments?page={page_number}

On the User, the URL being hit is http://localhost:3000/users/{:id}/comments?page={page_number}

Both URLs are hitting the index action of the Comments cont开发者_如何学Pythonroller.

My question is this: inside the index action, how do I determine if the {:id} provided is a user_id or a post_id so I can retrieve the desired comments.

Check for params[:user_id] and params[:post_id] in your Comments controller:

if params[:user_id]
  #call came from /users/ url
elsif params[:post_id]
  #call came from /posts/ url
else
  #call came from some other url
end

I like the Ryan Bates' way

class CommentsController
  before_action :load_commentable

  def index
    @comments = @commentable.comments.page(params[:page])
  end

  private

    def load_commentable
      klass = [Post, User].detect { |c| params["#{c.name.underscore}_id"] }
      @commentable = klass.find(params["#{klass.name.underscore}_id"])
    end
end