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Made the code of a validation example more robust #9993

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9c61a55
Made the code of a validation example more robust
javiereguiluz Jul 2, 2018
cc0e6b8
Added a check for empty strings
javiereguiluz Jul 3, 2018
f202e6d
Refactored the code
javiereguiluz Jul 3, 2018
c7ac3f7
Added a comment to explain why you should do this
javiereguiluz Jul 3, 2018
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9 changes: 9 additions & 0 deletions validation/custom_constraint.rst
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Expand Up @@ -59,11 +59,20 @@ The validator class is also simple, and only has one required method ``validate(

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;
use Symfony\Component\Validator\Exception\UnexpectedTypeException;

class ContainsAlphanumericValidator extends ConstraintValidator
{
public function validate($value, Constraint $constraint)
{
if (!is_string($value) && !(is_object($value) && method_exists($value, '__toString'))) {
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Now that =I review this, I've got a comment :). If a constraint allows casting an object to null then it should do so for any scalar. What about changing is_string to is_scalar? I can see that it's done here for example https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Validator/Constraints/EmailValidator.php#L77.

Also by convention; a constraint should not test empty value, for this a NotNull or NotBlank constraint should be used. So it misses:

if (null === $value || '' === $value) {
    return;
}

at first.

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I disagree with the proposed is_scalar() change. Even the error message of the validator says: The string "{{ string }}" contains an illegal character ... so this must only work with strings, right?

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I've added this:

if ('' === $value) {
    return;
}

Should it contain a trim($value) call too? Thanks!

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Hmm, casting should be ok, it's about changing the representation to make it fit, then throw an exception if it's not possible. I think we should stay consistent, if we want to keep is_string that strict, then let's remove the __toString() check.

Trimming is not as it alters the given value. Fortunately this will soon be opt-in symfony/symfony#26484.

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@HeahDude I made more changes according to your comments. Thanks for the reviews and for your patience 🙏

throw new UnexpectedTypeException($value, 'string');
}

if ('' === $value) {
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null must be check too.

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But the null value would never be checked. We throw an exception if !is_string() above.

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This check must be moved before indeed, and test null.

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@HeahDude HeahDude Jul 3, 2018 •
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The reason is that the constraint should not throw or invalid empty values, or it would superseed other constraints responsibility.

return;
}

if (!preg_match('/^[a-zA-Z0-9]+$/', $value, $matches)) {
// If you're using the new 2.5 validation API (you probably are!)
$this->context->buildViolation($constraint->message)
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