How to Use a Form without a Data Class
======================================

In most cases, a form is tied to an object, and the fields of the form get
and store their data on the properties of that object. This is what
:doc:`the main article on forms </forms>` is about.

But sometimes, you may want to use a form without a class, and get back an
array of the submitted data. The ``getData()`` method allows you to do
exactly that::

    // src/Controller/ContactController.php
    namespace App\Controller;

    use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
    use Symfony\Component\HttpFoundation\Request;
    use Symfony\Component\HttpFoundation\Response;
    // ...

    class ContactController extends AbstractController
    {
        public function contact(Request $request): Response
        {
            $defaultData = ['message' => 'Type your message here'];
            $form = $this->createFormBuilder($defaultData)
                ->add('name', TextType::class)
                ->add('email', EmailType::class)
                ->add('message', TextareaType::class)
                ->add('send', SubmitType::class)
                ->getForm();

            $form->handleRequest($request);

            if ($form->isSubmitted() && $form->isValid()) {
                // data is an array with "name", "email", and "message" keys
                $data = $form->getData();
            }

            // ... render the form
        }
    }

By default, a form actually assumes that you want to work with arrays of
data, instead of an object. There are exactly two ways that you can change
this behavior and tie the form to an object instead:

#. Pass an object when creating the form (as the first argument to ``createFormBuilder()``
   or the second argument to ``createForm()``);

#. Declare the ``data_class`` option on your form.

If you *don't* do either of these, then the form will return the data as
an array. In this example, since ``$defaultData`` is not an object (and
no ``data_class`` option is set), ``$form->getData()`` ultimately returns
an array.

.. tip::

    You can also access POST values (in this case "name") directly through
    the request object, like so::

        $request->getPayload()->get('name');

    Be advised, however, that in most cases using the ``getData()`` method is
    a better choice, since it returns the data (usually an object) after
    it's been transformed by the Form component.

Adding Validation
-----------------

The only missing piece is validation. Usually, when you call ``$form->handleRequest($request)``,
the object is validated by reading the constraints that you applied to that
class. If your form is mapped to an object (i.e. you're using the ``data_class``
option or passing an object to your form), this is almost always the approach
you want to use. See :doc:`/validation` for more details.

.. _form-option-constraints:

But if the form is not mapped to an object and you instead want to retrieve an
array of your submitted data, how can you add constraints to the data of
your form?

Constraints At Field Level
~~~~~~~~~~~~~~~~~~~~~~~~~~

One possibility is to set up the constraints yourself, and attach them to the individual
fields. The overall approach is covered a bit more in :doc:`this validation article </validation/raw_values>`,
but here's a short example::

    use Symfony\Component\Form\Extension\Core\Type\TextType;
    use Symfony\Component\Form\FormBuilderInterface;
    use Symfony\Component\Validator\Constraints\Length;
    use Symfony\Component\Validator\Constraints\NotBlank;

    public function buildForm(FormBuilderInterface $builder, array $options): void
    {
        $builder
            ->add('firstName', TextType::class, [
                'constraints' => new Length(['min' => 3]),
            ])
            ->add('lastName', TextType::class, [
                'constraints' => [
                    new NotBlank(),
                    new Length(['min' => 3]),
                ],
            ])
        ;
    }

.. tip::

    If you are using validation groups, you need to either reference the
    ``Default`` group when creating the form, or set the correct group on
    the constraint you are adding::

        new NotBlank(['groups' => ['create', 'update']]);

.. tip::

    If the form is not mapped to an object, every object in your array of
    submitted data is validated using the ``Symfony\Component\Validator\Constraints\Valid``
    constraint, unless you :doc:`disable validation </form/disabling_validation>`.

.. warning::

    When a form is only partially submitted (for example, in an HTTP PATCH
    request), only the constraints from the submitted form fields will be
    evaluated.

Constraints At Class Level
~~~~~~~~~~~~~~~~~~~~~~~~~~

Another possibility is to add the constraints at the class level.
This can be done by setting the ``constraints`` option in the
``configureOptions()`` method::

    use Symfony\Component\Form\Extension\Core\Type\TextType;
    use Symfony\Component\Form\FormBuilderInterface;
    use Symfony\Component\OptionsResolver\OptionsResolver;
    use Symfony\Component\Validator\Constraints\Length;
    use Symfony\Component\Validator\Constraints\NotBlank;

    public function buildForm(FormBuilderInterface $builder, array $options): void
    {
        $builder
            ->add('firstName', TextType::class)
            ->add('lastName', TextType::class);
    }

    public function configureOptions(OptionsResolver $resolver): void
    {
        $constraints = [
            'firstName' => new Length(['min' => 3]),
            'lastName' => [
                new NotBlank(),
                new Length(['min' => 3]),
            ],
        ];

        $resolver->setDefaults([
            'data_class' => null,
            'constraints' => $constraints,
        ]);
    }

This means you can also do this when using the ``createFormBuilder()`` method
in your controller::

    $form = $this->createFormBuilder($defaultData, [
            'constraints' => [
                'firstName' => new Length(['min' => 3]),
                'lastName' => [
                    new NotBlank(),
                    new Length(['min' => 3]),
                ],
            ],
        ])
        ->add('firstName', TextType::class)
        ->add('lastName', TextType::class)
        ->getForm();
