title: Laravel Validation: check why validator failed
body: <p>If there a way to check whether or not the validator failed specifically because of the <code>unique</code> rule?</p>
  
  <pre><code>$rules = array(
              'email_address' =&gt; 'required|email|unique:users,email',
              'postal_code' =&gt; 'required|alpha_num',
          );
  
          $messages = array(
              'required' =&gt; 'The :attribute field is required',
              'email' =&gt; 'The :attribute field is required',
              'alpha_num' =&gt; 'The :attribute field must only be letters and numbers (no spaces)'
          );
  
          $validator = Validator::make(Input::all(), $rules, $messages);
  
          if ($validator-&gt;fails()) {
  </code></pre>
  
  <p>In laymans terms, I basically want to know: "did the validation fail because the email_address was not unique?"</p>