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New in Symfony 5.3: Form Handler Helper

Kévin Dunglas

Contributed by
Kévin Dunglas
in #40799.

The recommended way of processing Symfony forms is to use a single action for both rendering the form and handling the form submit.

This is how it looks in practice:

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// src/Controller/ConferenceController.php
// ...
#[Route('/{id}/edit', name: 'conference_edit', methods: ['GET', 'POST'])]
public function edit(Request $request, Conference $conference): Response
{
    $form = $this->createForm(ConferenceType::class, $conference);

    $form->handleRequest($request);
    if ($form->isSubmitted() && $form->isValid()) {
        // do something with the $conference object
        // (e.g. persist it in the database)

        return $this->redirectToRoute('conference_show', [
            'id' => $conference->getId(),
        ]);
    }

    return $this->render('conference/edit.html.twig', [
        'form' => $form->createView(),
    ]);
}

When using libraries such as Symfony UX Turbo this simple form handling is not enough and you have to follow the HTTP protocol strictly (e.g. if the form is submitted but invalid, the response must have a HTTP 422 status code).

In order to simplify the form handling in those cases, Symfony 5.3 adds a new (optional) helper to handle forms. This helper is defined in the AbstractController base controller as a new method called handleForm().

This is how the previous example looks when using the new helper:

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// src/Controller/ConferenceController.php
// ...
#[Route('/{id}/edit', name: 'conference_edit', methods: ['GET', 'POST'])]
public function edit(Request $request, Conference $conference): Response
{
    return $this->handleForm(
        $this->createForm(ConferenceType::class, $conference),
        $request,
        function (FormInterface $form) use ($conference) {
            // do something with the $conference object
            // (e.g. persist it in the database)

            return $this->redirectToRoute(
                'conference_show',
                ['id' => $conference->getId()],
                Response::HTTP_SEE_OTHER
            );
        },
        function (FormInterface $form) {
            return $this->render('conference/edit.html.twig', [
                'form' => $form->createView(),
            ]);
        }
    );
}

The signature of the handleForm() method is:

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handleForm(FormInterface $form, Request $request, callable $onSuccess, callable $render): Response

Both $onSuccess and $render callables must return a Response object. This is how it works in practice:

  • if the form is not submitted, the $render callable is called;
  • if the form is submitted but invalid, the $render callable is called and a 422 HTTP status code is set if the current status hasn’t been customized;
  • if the form is submitted and valid, the $onSuccess callable is called (which is usually where you persist the data and return the 303 HTTP redirection).

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