title: Rails 3.2 Validation - Multiple Fields
body: <p>I have an award model.  The NOMINATOR selects himself from a dropdown list, then selects the NOMINEE from another dropdown list.</p>
  
  <p>How can I disallow self-nomination via a validation in the model?  In other words, the nominator cannot select himself from the nominee selection list.</p>
  
  <pre><code>class Award &lt; ActiveRecord::Base
    belongs_to :nominator, :class_name =&gt; 'Employee', :foreign_key =&gt; 'nominator_id'
    belongs_to :nominee, :class_name =&gt; 'Employee', :foreign_key =&gt; 'nominee_id'
    validates :nominator_id, :nominee_id, :award_description, :presence =&gt; true
  end
  </code></pre>
  
  <p>Thanks in advance!</p>