TransformerInterface

Raxos\Contract\Http\Validate\TransformerInterface is an extension point for raxos/http. Implement it, usually as a PHP attribute, to reshape an incoming request value into the type your application actually wants to work with.

Signature

interface TransformerInterface
{
    public function transform(mixed $value): mixed;
}

The interface is templated (@template T of mixed), so an implementation is documented as returning T.

Methods

transform(mixed $value): mixed

Turns the raw, decoded request value into the target value. Throws a TransformerExceptionInterface when the input cannot be transformed.

Notes

• Transformers run as part of raxos/http's request model validation, next to the constraints described in raxos/http's validation docs.
• A single class can implement both TransformerInterface and ConstraintAttributeInterface, so a value can be checked and reshaped by the same attribute.
• This is a typical extension point: raxos/http calls into it, your application supplies the implementation. See extension points.

Example

<?php
declare(strict_types=1);

namespace App\Http\Constraint;

use Attribute;
use Override;
use Raxos\Contract\Http\Validate\TransformerInterface;
use Raxos\Http\Validate\Error\InvalidValueTransformerException;

#[Attribute(Attribute::TARGET_PROPERTY)]
final readonly class CommaSeparatedList implements TransformerInterface
{
    #[Override]
    public function transform(mixed $value): array
    {
        if (!is_string($value)) {
            throw new InvalidValueTransformerException('Expected a comma separated string.');
        }

        return array_map(trim(...), explode(',', $value));
    }
}