3_7.md

3.7 Custom constraints

If you have your own Symfony constraint, implement the matching constraint on the JavaScript side too. Register it in Svaroh.constraints under the full PHP class name with the namespace separators removed.

For example, a PHP constraint:

<?php

// src/Validator/Constraints/ContainsAlphanumeric.php
namespace App\Validator\Constraints;

use Symfony\Component\Validator\Constraint;

class ContainsAlphanumeric extends Constraint
{
    public string $message = 'The string "%string%" contains an illegal character: it can only contain letters or numbers.';
}

<?php

// src/Validator/Constraints/ContainsAlphanumericValidator.php
namespace App\Validator\Constraints;

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

class ContainsAlphanumericValidator extends ConstraintValidator
{
    public function validate(mixed $value, Constraint $constraint): void
    {
        if (!is_string($value) || '' === $value) {
            return;
        }

        if (!preg_match('/^[a-zA-Z0-9]+$/', $value)) {
            $this->context->buildViolation($constraint->message)
                ->setParameter('%string%', $value)
                ->addViolation()
            ;
        }
    }
}

requires this JavaScript constraint:

<script type="text/javascript">
    Svaroh.constraints.AppValidatorConstraintsContainsAlphanumeric = function() {
        /**
         * This value will be filled with the real message received from the PHP constraint.
         */
        this.message = '';

        /**
         * This method is required.
         * It should return an error message or an array of messages.
         */
        this.validate = function(value) {
            if (value.length && !/^[a-zA-Z0-9]+$/.test(value)) {
                return this.message.replace('%string%', value);
            }

            return [];
        };

        /**
         * Optional method.
         */
        this.onCreate = function() {
            // Put setup logic here if the constraint needs it.
        };
    };
</script>

Svaroh is the namespace of the library, as described in the README. Constraints declared as a global function of the same name still work:

<script type="text/javascript">
    function AppValidatorConstraintsContainsAlphanumeric() {
        // ...
    }
</script>

This form is deprecated and support for it will be dropped in a future release, so prefer the namespace for new code. Note that a global cannot replace a constraint the bundle ships: the namespace is looked up first.