CustomerController.php

 public function assignCaseManagerAction($id) {
        $em = $this->getDoctrine()->getManager();

        $customer = $this->getCustomer($id);
        $request = $this->getRequest();

        if (!$customer) {
            throw $this->createNotFoundException('Unable to find Customer entity.');
        }

        $form = $this->createForm(new CustomerCaseManagerType(), $customer);

        if($request->getMethod() == 'POST')
        {
            $form->bindRequest($request);
            if ($form->isValid()) {
                $em->persist($customer);
                $this->getLogger()->addAccessItem($customer, $this->getUser(), "Case Manager Updated.", false);
                $em->flush();

                return $this->redirect($this->generateUrl('customer_show', array('id' => $id)));
            }
        }

        return $this->render('EcsCrmBundle:Customer:caseManager.html.twig', array(
            'customer'      => $customer,
            'form'   => $form->createView(),
        ));
    }