title: Constraint Validator validates Entity before Entity is ready in Symfony 2
body: <p>My Symfony2 (2.4.2) application has a form, and an entity which I have set some validation constraints on some fields. One of the entity's variables is an array which should not be blank.</p>
  
  <p>The form has a field which is not mapped to the entity directly. The input is a comma-delimited string; this string will be <code>preg_split</code> into an array and saved to the instance variable aforementioned. This operation is triggered by <code>FormEvents::POST_SUBMIT</code>.</p>
  
  <p>However, when I submit the form, even though the input string is not empty, the form shows that the validation fails. I did a bit of debugging and found that the validation actually happens before <code>FormEvents::POST_SUBMIT</code>. I have tried other <code>FormEvents</code> but no luck.</p>
  
  <p>Is there a way to trigger the event before the validation?</p>
  
  <p>Note: The scenario above is shortened, it'd be too long for me to ask a question if the context is my real application.</p>