title: defineing unique constraint in play framework 2
body: <p>i have a user model which has an Id managed by the framework but also an email attribute
  i want the email to be unique and at the moment im doing it using</p>
  
  <pre><code>@Email
  @Required
  @Column(unique=true)
  public String email;
  </code></pre>
  
  <p>this works fine but its throwing an PersistenceException.
  Does the play framework has a validation for this to be handeled at the form level.
  I want to avoid try catch blocks around my user.save()</p>