title: How to validate the date such that it is after today in Rails?
body: <p>I have an Active Record model that contains attributes: expiry_date. How do I go about validating it such that it is after today(present date at that time)? I am totally new to Rails and ruby and I couldn't find a similar question answering exactly this?</p>
  
  <p>I am using Rails 3.1.3 and ruby 1.8.7</p>