Event/RequestListener.php
public function onKernelRequest(GetResponseEvent $event)
    {
        if (!$event->isMasterRequest()) {
            // do nothing if it's not the master request
            return;
        }

        $request = $event->getRequest();

        if (!$request->isMethod('post')) {
            // do nothing if it's not a post request
            return;
        }

        try {
            /** @var FormInterface $form */
            $form = $this->formBuilder->buildByRequest($request);

            if (!$form || !$form->isSubmitted() || !$form->isValid()) {
                // do nothing when no form was found or not valid
                return;
            }
        } catch (\Exception $e) {
            // Catch all exception on build form by request
            return;
        }

        /** @var Dynamic $dynamic */
        $dynamic = $form->getData();
        $configuration = $this->formConfigurationFactory->buildByDynamic($dynamic);
        $dynamic->setLocale($request->getLocale()); // Need to be set to request locale for shadow pages, configuraiton will hold the original locale

        if ($this->formHandler->handle($form, $configuration)) {
            $serializedObject = $dynamic->getForm()->serializeForLocale($dynamic->getLocale(), $dynamic);
            $dynFormSavedEvent = new DynFormSavedEvent($serializedObject, $dynamic);
            $this->eventDispatcher->dispatch(DynFormSavedEvent::NAME, $dynFormSavedEvent);

            $response = new RedirectResponse('?send=true');
            $event->setResponse($response);
        }
    }
public function onKernelRequest(GetResponseEvent $event)
    {
        if (!$event->isMasterRequest()) {
            // do nothing if it's not the master request
            return;
        }

        $request = $event->getRequest();

        if (!$request->isMethod('post')) {
            // do nothing if it's not a post request
            return;
        }

        try {
            /** @var FormInterface $form */
            $form = $this->formBuilder->buildByRequest($request);

            if (!$form || !$form->isSubmitted() || !$form->isValid()) {
                // do nothing when no form was found or not valid
                return;
            }
        } catch (\Exception $e) {
            // Catch all exception on build form by request
            return;
        }

        /** @var Dynamic $dynamic */
        $dynamic = $form->getData();
        $configuration = $this->formConfigurationFactory->buildByDynamic($dynamic);
        $dynamic->setLocale($request->getLocale()); // Need to be set to request locale for shadow pages, configuraiton will hold the original locale

        if ($this->formHandler->handle($form, $configuration)) {
            $serializedObject = $dynamic->getForm()->serializeForLocale($dynamic->getLocale(), $dynamic);
            $dynFormSavedEvent = new DynFormSavedEvent($serializedObject, $dynamic);
            $this->eventDispatcher->dispatch(DynFormSavedEvent::NAME, $dynFormSavedEvent);

            $response = new RedirectResponse('?send=true');
            $event->setResponse($response);
        }
    }
On Kernel request.

@param GetResponseEvent $event