title: How do I trigger form validation without binding a request?
body: <p>I have a very long order form that enables saving drafts. If saved as draft, only order name is required but when actually placing an order a more thorough validation is required. I implemented this by using different validation groups. When editing the order I display two buttons: "Save draft" and "Place order". Each of them performs validation using a different validation group.</p>
  
  <p>But now I would like to make a button on the list of orders which enables to change order status from 'draft' to 'placed' directly. To do so, validation must be performed without displaying edit form and submitting it. I would just like to validate the entity that is already in the database. I can use the validator service and everything is simple as long as the data is valid. But in case data isn't valid, I would like to redirect user to the edit form with fields with missing data highlighted. The idea seems to load data from database into the form and run validation as if that data were sent using a browser but execution of this doesn't seem to be trivial because Symfony2 triggers validation on form only when binding the request.</p>
  
  <p>I was going through the Symfony source code and found s class called Symfony\Component\Form\Extension\Validator\EventListener\ValidationListener. It seems to attach itself on the FormEvents::POST_SUBMIT event. Is there a way to trigger this event manually from the controller without request binding? Or are there any alternative approaches to my problem? </p>