CustomValidators.md

Custom Validators

Custom Validators allow to implement specific rules and error messages for the submitted values. Validators implement the \Neos\Flow\Validation\Validator\ValidatorInterface which is made comfortable with the \Neos\Flow\Validation\Validator\AbstractValidator base class that reduces the effort to implementing a single isValid() Method. The behavior of validators can be configured via options. All found errors passed to the addError() method and will be combined with results other validators may return.

ATTENTION: The validator resolver searches validators in the namespace __PackageNamespace__\Validation\Validator\__ValidatorName__Validator when addressed via __PackageKey__:__ValidatorName__.

Flow validation documentation: https://flowframework.readthedocs.io/en/stable/TheDefinitiveGuide/PartIII/Validation.html

<?php
declare(strict_types=1);

namespace Vendor\Site\Validation\Validator;

use Neos\Flow\Validation\Validator\AbstractValidator;

class AllowedValuesValidator extends AbstractValidator
{
    /**
     * @var boolean
     */
    protected $acceptsEmptyValues = false;

    /**
     * @var mixed[]
     */
    protected $supportedOptions = array(
        'allowedValues' => array([], 'Array of allowed values', 'array', false),
    );

    /**
     * @param mixed $value
     * @return void
     */
    protected function isValid($value)
    {
        if (!in_array( $value, $this->options['allowedValues'])) {
            $this->addError('Some values are more correct than others.', 123456789);
        }
    }
}

The custom validator can now be used in fusion forms.

prototype(Vendor.Site:Content.FormExample) < prototype(Neos.Fusion.Form:Runtime.RuntimeForm) {

    process {
        content = afx`
            <Neos.Fusion.Form:FieldContainer field.name="favoriteMovie" label="Favorite Movie">
                <Neos.Fusion.Form:Input />
            </Neos.Fusion.Form:FieldContainer>
        `

        schema {
            #
            # A custom validator is identified via PackageKey and ValidatorName seperated by a colon. 
            # The implementation is expected to be in the php namespace `__PackageNamespace__\Validation\Validator\__ValidatorName__Validator`
            # 
            favoriteMovie = ${Form.Schema.string().validator('Vendor.Site:AllowedValues', {allowedValues: ['Star Wars', 'Simpsons']})}
        }
    }
    
    ...