Ruby on Rails : Simple search engine using Ajax

After type words in the input field and wait awhile, the result will display at the partial page, no need to hit enter.

In views.rhtml

<%= javascript_include_tag "prototype" %>
Search : <%= text_field "article", "title" %>
<%= observe_field :article_title,
 :frequency => 1.0, 
 :update => 'article_list',
 :url => { :action => 'search' }, 
 :with => "'search=' + encodeURIComponent(value)"
%>
<div id = 'article_list'>
<%= render :partial => 'article', :collection => @articles %>
</div>

In partial page, _article.rhtml

Title: <%= article.title %><br>
Author: <%= article.author %>
<hr>

In controller.rb

def search
@articles = Article.find(:all, 
:conditions => ["lower(title) like ?", "%" + params[:search].downcase + "%"])

 if params[:search].to_s.size < 1
  @articles = Article.find(:all)
  render :partial => 'article', :collection => @articles
 else
  if @articles.size > 0
   render :partial => 'article', :collection => @articles
  else
   render :text => "Result not found!", :layout => false
  end
 end
end

** To wider search :
@articles = Article.find(:all, :conditions => ["lower(title) like ? and lower(type) like ?
and number like ?", "%" + params[:search][:title].downcase + "%",
"%" + params[:search][:type].downcase + "%", "%" + params[:search][:number] + "%"])

Prototype Helper : http://api.rubyonrails.org/classes/ActionView/Helpers/PrototypeHelper.html#M001645