Do not validate child constraints if form has no validation groups

[maryo]

Q	A
Branch?	3.4
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
Tests pass?	yes
License	MIT

If a form has Valid constraint and validation_groups set to an empty array (to disable validation) then its children were still validated using default validation group because FormValidator validated the form data using the empty array validation group here
https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Form/Extension/Validator/Constraints/FormValidator.php#L76

and then RecursiveContextualValidator treats the empty array as default validation group here.

https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Validator/Validator/RecursiveContextualValidator.php#L86

[maryo]

I've updated it because it has nothing to do with validation_groups being set as a callback, just a simple empty array is enough to reproduce the bug.

[HeahDude]

Hello @maryo, thank you for opening this issue.

It seems to be a doc issue to me, to disable validation you should define the validation_groups option to false instead.

[maryo]

@HeahDude Yeah. But according to this code
https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Form/Extension/Validator/Type/BaseValidatorExtension.php#L35
false is just an alias for an empty array but not in case validation_groups is a callback. Then it is not normalized. Then it just returns the callable and it is then then resolved inside FormValidator here
https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Form/Extension/Validator/Constraints/FormValidator.php#L183

If the callback returns false, then it actually validates it against group false. That's not such a problem but still a bug IMO.

And all the tests inside FormValidator also expect an empty array to disable validation. That's probably also because the normalization from false to [] inside BaseValidatorExtension is not triggered by calling FormValidator->validate(/*...*/) manually.

[HeahDude]

Ah yes when used with both the constraints option. Looks good. Thanks!

[fabpot]

Thank you @maryo.