_comment.html.erb

<% div_for comment do %>
  <h1>Commentaire ajouté par <%= comment.user.login %></h1>
  <p class="comment-body"><%= comment.comment %></p> 
  <p>Depuis <%= time_ago_in_words(comment.created_at)  %></p>
  <%= link_to 'Effacer commentaire', comment, :method => :delete, :class => "delete", :remote => true %>
<% end %> 

_index.html.erb

<span id="comments_count"><%= pluralize(@comment.count, "Commentaires") %></span>
<div id="comments">
	<%= render :partial => @comment, :locals => { :list => true}, :object => @client %>
	</div>
	<hr />
<div id="comment-notice"></div>
<h2>Commentaire pour ce <%= object.class %></h2> 
<% form_tag(comments_path, :remote => true)  do -%> 
  <%= hidden_field_tag 'comment[user_id]', current_user.id %> 
  <%= hidden_field_tag 'comment[commentable_id]', object.id %> 
  <%= hidden_field_tag 'comment[commentable_type]', object.class %> 
  <%= text_area_tag 'comment[comment]', nil, :style => 'width:100%; height:100px;' %> 
  <%= submit_tag 'Ajoutez' %>
<% end %> 

comments_controller.rb

class CommentsController < ApplicationController

  def create
    @client = Client.find(params[:comment][:commentable_id])
    @comment = @client.comments.new(params[:comment])
    @comment.user_id = current_user.id
    if @comment.save
      flash[:notice] = "Votre commentaire à correctement été ajouté."
      respond_to do |format|
      format.js
    end
    else # validation fails
      flash[:notice] = "Votre commentaire est vide."
      redirect_to :back
    end
  end

   def destroy
    puts ">>>> Destroying a comment <<<<"
    @comment = Comment.find(params[:id])
    puts "found comment>>> #{@comment}"
    @comment.destroy
    flash[:notice] = "Votre commentaire à correctement été effacé."
    respond_to do |format|
      format.js
    end
  end

end

create.js.erb

/* Insert a notice between the last comment and the comment form */
$("#comment-notice").html('<div class="flash notice"><%= escape_javascript(flash.delete(:notice)) %></div>');

/* Replace the count of comments */
$("#comments_count").html("<%= pluralize(Comment.count, 'Comment') %>");

/* Add the new comment to the bottom of the comments list */
$("#comments").append("<%= escape_javascript(render(@comment)) %>");

/* Highlight the new comment */
$("#comment_<%= @comment.id %>").effect("highlight", {}, 3000);

/* Reset the comment form */
$("#new_comment")[0].reset();

destroy.js.erb

/* Eliminate the comment by fading it out */
$('#comment_<%= @comment.id %>').fadeOut();
/* Replace the count of comments */
$("#comments_count").html("<%= pluralize(Comment.count, 'Comentari') %>");

show.html.erb

.............................. #show from my client controller.

    <div id="tagContent6" class="tagContent">
      <%= render :partial => "/comments/index", :object => @client %>
    </div>
	  
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