controllers\comments_controller.rb

class CommentsController < InheritedResources::Base

  def create
    @commentable = find_commentable
    @comment = @commentable.comments.build(params[:comment])
    @comment.user_id = current_user.id

    if @comment.save
      respond_to do |format|
        format.js
      end
      #redirect_to url_for(@commentable)
    else
      render :controller => @commentable.class.downcase.pluralize, :action => :show
    end
  end

  def find_commentable
    params.each do |name, value|
      if name =~ /(.+)_id$/
        return $1.classify.constantize.find(value)
      end
    end
    nil
  end

  def destroy
    @commentable = find_commentable
    @comment = Comment.find(params[:id])
    @comment.destroy
    respond_to do |format|
      format.js
    end
    #redirect_to url_for(@commentable)
  end

end

views/comments/_form.html.haml
= semantic_form_for [@commentable, @comment], :remote => true do |f|
  = f.inputs do
    = f.input :content, :as => :text, :input_html => { :rows => 5, :cols => 30 }
  = f.buttons do
    = f.commit_button :label => "Отправить"

views\comments\_comment.html.haml
%li.comment{ :id => "comment#{comment.id}"}
  = comment.user.username
  = simple_format comment.content
  - if current_user.id == comment.user_id
    = link_to "remove", [@commentable, @comment], :method => :delete, :remote => true, :class => :delete

views\comments\create.js.erb
$("#comment").append("<%= escape_javascript(render(@comment)) %>")

views\comments\destroy
$("#comment<%= @comment.id %>").fadeOut();

views\photos\show.html.haml
= image_tag (@photo.store_url)

#comment
  %ul
  - for comment in @photo.comments
    %li.comment{ :id => "comment#{comment.id}"}
      = comment.user.username
      = simple_format comment.content
      - if current_user.id == comment.user_id
        = link_to "remove", photo_comment_path(@photo.id, comment), :method => :delete, :remote => true, :class => :deletete

  = semantic_form_for [@commentable, @comment], :remote => true do |f|
    = f.inputs do
      = f.input :content, :as => :text, :input_html => { :rows => 5, :cols => 30 }
    = f.buttons do
      = f.commit_button :label => "Отправить"

#prev
  = link_to("Previous", @photo.album.previous_photo( @photo.album.photos.index(@photo) ))
#next
  = link_to("Next", @photo.album.next_photo( @photo.album.photos.index(@photo) ))

#back
  = link_to "Back To Album", user_album_path(@photo.album.user_id, @photo.album_id)

controllers\photos_controller.rb
class PhotosController < StoresController

  before_filter :fetch_photo, :only=> [:show]

  def new
    @photo = Photo.new(:album_id => params[:album_id])
  end

  def create
    @photo = Photo.new(params[:photo])
    if @photo.save
      flash[:notice] = "Successfully created file."
      redirect_to user_album_path(@photo.album.user_id, @photo.album_id)
    else
      render :action => 'new'
    end
  end

  def edit
    @photo = Photo.find(params[:id])
  end

  def update
    @photo= Photo.find(params[:id])
    if @photo.update_attributes(params[:photo])
      flash[:notice] = "Successfully updated file."
      redirect_to user_album_path(@photo.album.user_id, @photo.album_id)
    else
      render :action => 'edit'
    end
  end

  def destroy
    @photo = Photo.find(params[:id])
    @photo.destroy
    flash[:notice] = "Successfully destroyed file."
    redirect_to :back
  end

  def show
    @photo = Photo.find(params[:id])
    @comment = @commentable.comments.build
  end

  def fetch_photo
    @photo = @commentable = Photo.find(params[:id])
  end
end