[Form] Cannot use object of type Closure as array

[umpirsky]

Symfony version(s) affected: 4.2.11

How to reproduce

Have type defined like this:

class MyDateAndTimeType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->add('time', TimeType::class, $options);

        $builder->addModelTransformer(new MyDateAndTimeToDateTimeTransformer());
    }

    public function getBlockPrefix()
    {
        return 'data_and_time';
    }
}

You get this error when creating the form:

Cannot use object of type Closure as array

  at vendor/symfony/symfony/src/Symfony/Component/Form/Extension/Core/Type/TimeType.php:80

The problem is passing options to $builder->add('time', TimeType::class, $options) which carries:

  "empty_data" => Closure(FormInterface $form) {#2763 ▼
    class: "Symfony\Component\Form\Extension\Core\Type\FormType"
    this: FormType {#2569 …}
    parameters: {▶}
    file: "vendor/symfony/symfony/src/Symfony/Component/Form/Extension/Core/Type/FormType.php"
    line: "140 to 142"
  }

This used to work in 4.1

Additional context
Suspected changeset #29182.

[xabbuh]

Does this happen with 4.3 too? If so, could your create a small example application that allows to reproduce?

[umpirsky]

According to code I guess it does. I will try to create a reproducer when I have time.

[derrabus]

Why do you pass the $options array on to the add() method? That looks odd to me.

[umpirsky]

Yes, I fixed that, but it still feels like BC break.

[yceruto]

Even if passing the parent/resolved empty_data option to the TimeType field would be wrong here, I think TimeType is not taking into account the feasible Closure value that is allowed/documented for this empty_data option:

https://symfony.com/doc/current/reference/forms/types/form.html#empty-data:

If a form is compound, you can set empty_data as an array, object or closure. See the How to Configure empty Data for a Form Class article for more details about these options.

https://symfony.com/doc/current/form/use_empty_data.html#option-2-provide-a-closure:

Using a closure is the preferred method, since it will only create the object if it is needed.
The closure must accept a FormInterface instance as the first argument.

'empty_data' => function (FormInterface $form) {
    return $form->getConfig()->getCompound() ? ['hour' => 0, 'minute' => 0] : '00:00';
},

So the above example should also work for TimeType, isn't it?

[umpirsky]

Yeah, seems so.

[yceruto]

symfony/src/Symfony/Component/Form/Extension/Core/Type/TimeType.php

Lines 77 to 81 in ef0119a

	$emptyData = $builder->getEmptyData() ?: [];
	if (isset($emptyData['hour'])) {
	$hourOptions['empty_data'] = $emptyData['hour'];
	}

As we can't invoke the $emptyData() closure directly in the build process (because the form instance is not ready to be passed to the closure at that point) theoretically something like this can fix the error (unproven):

if ($emptyData instanceof \Closure) {
    $hourOptions['empty_data'] = static function (FormInterface $form) use ($emptyData) {
        $emptyData = $emptyData($form->getParent());

        return isset($emptyData['hour']) ? $emptyData['hour'] : '';
    };
} // elseif ...

@umpirsky would you like to give it a try? (bugfix in 3.4 branch)

[umpirsky]

Sorry, can't work on it now, it must wait.

[yceruto]

See #34123