Get the error from a form and send this error by rest

gistfile1.txt

public function createAction(Request $request)
	{
		$entity  = new Channel();
		$form = $this->createForm(new ChannelType(), $entity);
		$form->bind($request);
	
		if ($form->isValid()) {
			$this->get('api.model.channel_manager')->save($entity);
	
			$view = $this->view($entity, 201);
			return $this->handleView($view);
		}else{
			$form->getErrorsAsString(); //this return errors
                        $form->getErrors(); // this return array empty  

		}
		$view = $this->view($form, 400);
		return $this->handleView($view);

	}