Paginate on two collections on the same model

I am planning to add some pagination to a couple of models in my application and I feel like I am missing a key concept here. Here is my application:

class Gallery < ActiveRecord::Base

    has_many :photos
    has_many :comments

end

class GalleryController < ApplicationController

    def show
        # some process here
        @gallery = Gallery.find(params[:id])
    end

end

I would like to be able to paginate independently on both the photos and comments for the given gallery that I am displaying. I need this to be done with AJAX and I have a feeling that calling 'show' with a parameter for photos or galler开发者_JAVA技巧y is overkill (ie. why would I need to find the gallery if I am only looking for photos or comments).

How should I design this feature?

What is the alternative to calling GalleryController.show here?

I'd set it up like this:

class GalleriesController < ApplicationController
  def index
    @galleries = Gallery.paginate(params)
  end
end

class CommentsController < ApplicationController
  def index
    @comments = parent.comments.paginate(params)
  end

  def parent
    @parent ||= Gallery.find(params[:gallery_id])
  end
end

class PhotosController < ApplicationController
  def index
    @photos = parent.photos.paginate(params)
  end

  def parent
    @parent ||= Gallery.find(params[:gallery_id])
  end
end

# config/routes.rb
resources :galleries do
  resources :photos
  resources :comments
end

Then you just request:

/galleries/1/comments
/galleries/1/photos

Check out the inherited_resources gem for this nested model pattern.

But ideally you'd want to get this all in one request. Check out this post on the Presenter Pattern in Rails.

Hope that helps.

yes, i'd absolutely recommend using inherited_resources, as it saves you a lot of boilerplate code. just set up these resources as described by viatropos, add JSON-responder (with inherited_resources, its as easy as adding respond_to :json, :html to your controller). then on the ajax side use a tempting plugin, like jquery.tmpl or mustache.js or whatever, pre-render an item template for each resource, and then use ajax to retrieve your paginated data as JSON and render it into your templates. it's incredibly easy, but if you need a step by step howto, just ask.