# src/Acme/BlogBundle/Controller/DefaultController.php
public function newAction(Request $request)
{
   $task = new Task();
   $form = $this->createFormBuilder($task)
      ->add('task', 'text')
      ->add('dueDate', 'date')
      ->getForm();
   if ($request->getMethod() == 'POST') {
      $form->bindRequest($request);
      if ($form->isValid()) {
          // some actions ...
      return $this->redirect($this->generateUrl('task_success'));
}


# src/Acme/BlogBundle/Resources/config/validation.yml
Acme\BlogBundle\Entity\Task:
    properties:
        task:
            - NotBlank: { message: "test message" }