MyController.php

<?php

// ...

class MyController extends Controller
{
   /**
     * @Route("/", name="neuro_index")
     */
    public function indexAction()
    {
        $form = $this->createDonationForm();
        $amount = 0;
        $percentage = $amount / 6;

        return $this->render('AppBundle:NeuroFund:index.html.twig', array(
           'progress_amount' => $amount,
           'progress_percentage' => $percentage,
           'form' => $form->createView(),
        ));
    }

    /**
     * @Route("/donate", name="neuro_save_form")
     */
    public function donateFormAction(Request $request)
    {
        $form = $this->createDonationForm();
        
        $form->handleRequest($request);
        
        if ($form->isSubmitted() && $form->isValid()) {
           // yah! Let's handle the form submission and return some response
        }
        
        // ah, form wasn't valid, render it again with the errors...
        return $this->render('AppBundle:NeuroFund:index.html.twig', array(
           'progress_amount' => $amount,
           'progress_percentage' => $percentage,
           'form' => $form->createView(),
        ));
    }

    protected function createDonationForm()
    {
        $dform = new DonationForm();

        return $this->createFormBuilder($dform)
            ->setAction($this->generateUrl('neuro_save_form'))
            ->add('name', 'text')
            ->add('email', 'email')
            ->add('bankaccountnumber', 'text')
            ->add('isanonymous', 'checkbox', array('required' => false))
            ->add('donate', 'submit', array('label' => 'Donate!'))
            ->getForm();
    }
}