[Validator] When Constraint only works with public class properties

[ariCristina]

Symfony version(s) affected

6.2.2

Description

When trying to use the When constraint and it seems to be working only with public class properties; if the property is declared protected or private, it throws the error Cannot access protected property App\Model\ExampleModel::$mainProperty

How to reproduce

In a model class, let's say App\Model\ExampleModel::$mainProperty, we declare 2 properties, where property protected $secondaryProperty should depend on protected $mainProperty. Boit properties have public getters and setters.

Not working

// Has your website accepted online payments before?
    #[
        Assert\Choice([0, 1])
    ]
    protected ?int $mainProperty = 1;

    #[Assert\When(
        expression: 'this.mainProperty == 1',
        constraints: [
            new Assert\NotBlank(message: "validator.form.error")
        ],
    )]
    protected ?string $secondaryProperty;

Partially working - not throwing error anymore, but does not evaluate the conditional expression properly, meaning id does not throw the constraint validation message; form behaves like it does not have an error.

// Has your website accepted online payments before?
    #[
        Assert\Choice([0, 1])
    ]
    public ?int $mainProperty = 1;

    #[Assert\When(
        expression: 'this.mainProperty == 1',
        constraints: [
            new Assert\NotBlank(message: "validator.form.error")
        ],
    )]
    protected ?string $secondaryProperty;

Working - only when the expression is set explicitly to TRUE; now, the constraint's message it is present when trying to submit the form

// Has your website accepted online payments before?
    #[
        Assert\Choice([0, 1])
    ]
    protected ?int $mainProperty = 1;

    #[Assert\When(
        expression: 'true',
        constraints: [
            new Assert\NotBlank(message: "validator.form.error")
        ],
    )]
    protected ?string $secondaryProperty;

###Info - both properties have public getters and setters

    /**
     * @return int|null
     */
    public function getMainProperty(): ?int
    {
        return $this->mainProperty;
    }

    /**
     * @param bool|null $mainProperty
     *
     * @return ExampleModel
     */
    public function setMainProperty(?bool $mainProperty): ExampleModel
    {
        $this->mainProperty = (int)$mainProperty;

        return $this;
    }

    /**
     * @return string|null
     */
    public function getSecondaryProperty(): ?string
    {
        return $this->secondaryProperty;
    }

    /**
     * @param string|null $secondaryProperty
     *
     * @return ExampleModel
     */
    public function setSecondaryProperty(?string $secondaryProperty): ExampleModel
    {
        $this->secondaryProperty = $secondaryProperty;

        return $this;
    }

Possible Solution

No response

Additional Context

Where $previousOnlinePaymentsAccepted is $mainProperty and $acquirer is $secondaryProperty

Error:
Cannot access protected property App\Model\WebsiteDetails\WebsiteDetailsModel::$previousOnlinePaymentsAccepted

  at vendor/symfony/expression-language/Node/GetAttrNode.php:92
  at Symfony\Component\ExpressionLanguage\Node\GetAttrNode->evaluate(array('constant' => array('compiler' => object(Closure), 'evaluator' => object(Closure))), array('value' => null, 'this' => object(WebsiteDetailsModel)))
     (vendor/symfony/expression-language/ExpressionLanguage.php:59)
  at Symfony\Component\ExpressionLanguage\ExpressionLanguage->evaluate('this.previousOnlinePaymentsAccepted', array('value' => null, 'this' => object(WebsiteDetailsModel)))
     (vendor/symfony/validator/Constraints/WhenValidator.php:37)
  at Symfony\Component\Validator\Constraints\WhenValidator->validate(null, object(When))
     (vendor/symfony/validator/Validator/RecursiveContextualValidator.php:743)
  at Symfony\Component\Validator\Validator\RecursiveContextualValidator->validateInGroup(null, '00000000000005cd0000000000000000:App\\Model\\WebsiteDetails\\WebsiteDetailsModel:acquirer', object(PropertyMetadata), 'Default', object(ExecutionContext))
     (vendor/symfony/validator/Validator/RecursiveContextualValidator.php:588)
  at Symfony\Component\Validator\Validator\RecursiveContextualValidator->validateGenericNode(null, object(WebsiteDetailsModel), '00000000000005cd0000000000000000:App\\Model\\WebsiteDetails\\WebsiteDetailsModel:acquirer', object(PropertyMetadata), 'data.acquirer', array('Default'), null, 1, object(ExecutionContext))
     (vendor/symfony/validator/Validator/RecursiveContextualValidator.php:502)
  at Symfony\Component\Validator\Validator\RecursiveContextualValidator->validateClassNode(object(WebsiteDetailsModel), '00000000000005cd0000000000000000', object(ClassMetadata), 'data', array('Default'), null, 1, object(ExecutionContext))
     (vendor/symfony/validator/Validator/RecursiveContextualValidator.php:299)
  at Symfony\Component\Validator\Validator\RecursiveContextualValidator->validateObject(object(WebsiteDetailsModel), 'data', array('Default'), 1, object(ExecutionContext))
     (vendor/symfony/validator/Validator/RecursiveContextualValidator.php:133)
  at Symfony\Component\Validator\Validator\RecursiveContextualValidator->validate(object(WebsiteDetailsModel), null, array('Default'))
     (vendor/symfony/form/Extension/Validator/Constraints/FormValidator.php:105)
  at Symfony\Component\Form\Extension\Validator\Constraints\FormValidator->validate(object(Form), object(Form))
     (vendor/symfony/validator/Validator/RecursiveContextualValidator.php:743)
  at Symfony\Component\Validator\Validator\RecursiveContextualValidator->validateInGroup(object(Form), '00000000000006cf0000000000000000', object(ClassMetadata), 'Default', object(ExecutionContext))
     (vendor/symfony/validator/Validator/RecursiveContextualValidator.php:474)
  at Symfony\Component\Validator\Validator\RecursiveContextualValidator->validateClassNode(object(Form), '00000000000006cf0000000000000000', object(ClassMetadata), '', array('Default'), null, 1, object(ExecutionContext))
     (vendor/symfony/validator/Validator/RecursiveContextualValidator.php:299)
  at Symfony\Component\Validator\Validator\RecursiveContextualValidator->validateObject(object(Form), '', array('Default'), 1, object(ExecutionContext))
     (vendor/symfony/validator/Validator/RecursiveContextualValidator.php:133)
  at Symfony\Component\Validator\Validator\RecursiveContextualValidator->validate(object(Form), null, array('Default'))
     (vendor/symfony/validator/Validator/RecursiveValidator.php:82)
  at Symfony\Component\Validator\Validator\RecursiveValidator->validate(object(Form), null, null)
     (vendor/symfony/validator/Validator/TraceableValidator.php:58)
  at Symfony\Component\Validator\Validator\TraceableValidator->validate(object(Form))
     (vendor/symfony/form/Extension/Validator/EventListener/ValidationListener.php:46)
  at Symfony\Component\Form\Extension\Validator\EventListener\ValidationListener->validateForm(object(PostSubmitEvent), 'form.post_submit', object(EventDispatcher))
     (vendor/symfony/event-dispatcher/EventDispatcher.php:206)
  at Symfony\Component\EventDispatcher\EventDispatcher->callListeners(array(object(Closure), object(Closure), object(Closure)), 'form.post_submit', object(PostSubmitEvent))
     (vendor/symfony/event-dispatcher/EventDispatcher.php:56)
  at Symfony\Component\EventDispatcher\EventDispatcher->dispatch(object(PostSubmitEvent), 'form.post_submit')
     (vendor/symfony/event-dispatcher/ImmutableEventDispatcher.php:30)
  at Symfony\Component\EventDispatcher\ImmutableEventDispatcher->dispatch(object(PostSubmitEvent), 'form.post_submit')
     (vendor/symfony/form/Form.php:591)
  at Symfony\Component\Form\Form->submit(array())

[stof]

the Symfony ExpressionLanguage does not have the same magic than Twig for the . operator (because its goal is to not have any runtime when compiling to an expression). So .mainProperty really means accessing the property mainProperty, not also trying to use its getter when it is not public. Use .getMainProperty() in your expression and it will work.

[ariCristina]

the Symfony ExpressionLanguage does not have the same magic than Twig for the . operator (because its goal is to not have any runtime when compiling to an expression). So .mainProperty really means accessing the property mainProperty, not also trying to use its getter when it is not public. Use .getMainProperty() in your expression and it will work.

I tried with expression: 'this.getPreviousOnlinePaymentsAccepted() == 1', and, indeed, does not throw the exception from the first example; in this case, the docs should be updated, because they did not mirror this behavior: https://symfony.com/doc/current/reference/constraints/When.html

This also fixes my problem, the only reason it was not working was a coding logic when initialize the form; this.getPreviousOnlinePaymentsAccepted() == 0' returned true.

Much appreciated; I was not very familiar with the Symfony ExpressionLanguage.

[stof]

I opened symfony/symfony-docs#17905 to update the documentation with a working example.

I'm closing this issue here as there is no bug in Symfony itself.