title: Symfony2 Container Aware Form Type
body: <p>Is there a way to make a form type container aware?</p>
  
  <p>As an example I have 3 entities Account, User and Event. Users have ManyToMany relationship in order to associate many users with many other users (called approvers), reason for this is so that an Event created by a User can have a list of Users who area able approve it. In the User edit form where I have an approvers multiple select field the list needs to be filtered by Account so I need my form type to be container aware in order to filter the list of available Users by Account ID.</p>
  
  <p>Am I right in thinking that making the form type container aware is the right way to go? I'd like to use the entity manager to filter a list of Users by Account.</p>