[Form] getClickedButton() missing in FormInterface returned by builder

[ThomasLandauer]

Symfony version(s) affected: 4.4

phpstan reports:

Call to an undefined method Symfony\Component\Form\FormInterface::getClickedButton()

According to @althaus this is because getClickedButton() is not included in the FormInterface returned by the builder, see phpstan/phpstan-symfony#12 (comment)

[ThomasLandauer]

And when trying it the other way as explained at https://symfony.com/doc/current/form/multiple_buttons.html

$form->get('saveAndAdd')->isClicked()

... I'm getting:

Call to an undefined method Symfony\Component\Form\FormInterface::isClicked()

[xabbuh]

getClickedButton() is not part of the interface as it wouldn't make much sense for a Button implementation which also implements the FormInterface. Likewise isClicked() is not part of the interface as it is only useful for buttons.

If you want to stop PHPStan complaining about it without adding it to the baseline, you can do something like this:

if ($form instanceof Form) {
    $button = $form->getClickedButton();
}

// or

/** @var Form $form */
$button = $form->getClickedButton();

I don't think there is anything we can do in the Form component about this.

[ro0NL]

at least SF anticipates each form implementation may implement this:

symfony/src/Symfony/Component/Form/Extension/Validator/Constraints/FormValidator.php

Lines 167 to 169 in 80cc6bd

	if (method_exists($form, 'getClickedButton')) {
	$clickedButton = $form->getClickedButton();
	}

which to me is a hint it's missing in some contract, somewhere

[xabbuh]

@ro0NL Technically there could be other implementations of the FormInterface. So the FormValidator takes the safe path and performs this check first to prevent type errors even if it's probably always true in a typical Symfony application.

I am closing as explained in #35277 (comment).