title: How to catch grails.validation.ValidationException?
body: <p>I have simple domain:</p>
  
  <pre><code>package app
  
     class Customers {
     String CUSTOMER
     String NOTE
  
     static mapping = {
        version false
        id column: 'ID_CUSTOMER', type: 'long',
           generator: 'sequence',
           params: [sequence: 'CUSTOMER_SEQ']
     }
  
     static constraints = {
        CUSTOMER(nullable: false, blank: false, unique: ['NOTE'])
        NOTE(nullable: true, blank: true) 
     }
  }
  </code></pre>
  
  <p>Columns and constraints are created properly in database (I want constraint on customer and note together), but instead of getting:</p>
  
  <pre><code>grails.validation.**ValidationException**
  </code></pre>
  
  <p>I am getting:</p>
  
  <pre><code>Message: Hibernate operation: could not execute statement; SQL [n/a]; ORA-00001: unique constraint (TEST2.UNIQUE_CUSTOMER_NOTE) violated
  ; nested exception is java.sql.SQLIntegrityConstraintViolationException: ORA-00001: unique constraint (TEST2.UNIQUE_CUSTOMER_NOTE) violated
  </code></pre>
  
  <p>Shouldn't I get <strong>ValidationException</strong> when constrains are violated?</p>
  
  <p>Controller code is standard auto code generated by the <code>generate-all</code> script.</p>