How to Use a Form without a Data Class

3.3 version

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 exactly what you've seen so far in this article with the Task class.

But sometimes, you may just want to use a form without a class, and get back an array of the submitted data. This is actually really easy:

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// make sure you've imported the Request namespace above the class
use Symfony\Component\HttpFoundation\Request;
// ...

public function contactAction(Request $request)
{
    $defaultData = array('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:

  1. Pass an object when creating the form (as the first argument to createFormBuilder() or the second argument to createForm());
  2. 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->request->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->isValid(), 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 Validation for more details.

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

The answer is to setup the constraints yourself, and attach them to the individual fields. The overall approach is covered a bit more in this validation article, but here's a short example:

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

$builder
   ->add('firstName', TextType::class, array(
       'constraints' => new Length(array('min' => 3)),
   ))
   ->add('lastName', TextType::class, array(
       'constraints' => array(
           new NotBlank(),
           new Length(array('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.

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new NotBlank(array('groups' => array('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 disable validation.


This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.