title: Validating field uniqueness via Ajax call with appropriate message in Rails 3
body: <p>I am trying to do a Rails + AJAX call validation to check for the uniqueness of a field, by crawling the back end DB and return an appropriate message based on the result.</p>
  
  <p>I am on Rails 3.0.11.</p>
  
  <p>Is there a Ruby gem, JS plugin or jQuery plugin that I can make use of?</p>