Composite - grouping multiple validation rules

Composite allows to group multiple rules and configure the common skipping options, such as skipOnEmpty, skipOnError and when, for the whole set only once instead of repeating them in each rule:

use Yiisoft\Validator\Rule\Composite;
use Yiisoft\Validator\Rule\Email;
use Yiisoft\Validator\Rule\Length;

new Composite(
    [
        new Length(max: 255),
        new Email(),
    ],
    skipOnEmpty: true,
);

Reusing multiple rules / single rule with the same options

Composite is one of the few built-in rules that is not final. This means that you can extend it and override the getRules() method to create a reusable set of rules:

use Yiisoft\Validator\Rule\Composite;
use Yiisoft\Validator\Rule\Length;
use Yiisoft\Validator\Rule\Regex;

final class UsernameRuleSet extends Composite
{
    public function getRules(): array
    {
        return [
            new Length(min: 2, max: 20),
            new Regex('~^[a-z_\-]*$~i'),
        ];
    }
}

And use it just like a single regular rule:

use Yiisoft\Validator\Validator;

$result = (new Validator())->validate('John', new UsernameRuleSet());

It can also be combined with Nested rule to reuse rules for multiple attributes:

use Yiisoft\Validator\Rule\Composite;
use Yiisoft\Validator\Rule\Nested;
use Yiisoft\Validator\Rule\Number;

final class CoordinatesRuleSet extends Composite
{
    public function getRules(): array
    {
        return [
            new Nested(
                'latitude' => new Number(min: -90, max: 90),
                'longitude' => new Number(min: -90, max: 90),
            ),
        ];
    }
}

Even the problem of reusing only one rule with the same arguments can be solved with Composite:

use Yiisoft\Validator\Rule\Composite;
use Yiisoft\Validator\Rule\Number;

final class ChartCoordinateRuleSet extends Composite
{
    public function getRules(): array
    {
        return [new Number(min: -10, max: 10)];
    }
}

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