README

Validates a set of input values against a per-field list of rules. Stateless — the rules travel with each call, so one Validator can be shared and autowired. Ships no ServiceProvider; the validator has no dependencies to bind.

Usage

For each field the rules run in order and the validator short-circuits on the first failure — there's no point computing messages a single-message-per-field UI (an htmx form) will never show.

$result = $validator->validate($data, [
    'email' => [new Required, new Pattern('/\A.+@.+\z/')],
    'name'  => [new Required, new MaxLength(120)],
]);

if ($result->fails()) {
    $errors = $result->errors();      // ['email' => 'first message', ...]
    $first  = $result->first('email'); // or null if it passed
}

Result carries at most one message per field (the first rule that failed), which is the shape view models consume.

Note the \A/\z anchors in the pattern: with ^/$, PCRE's $ tolerates a trailing newline (so "a@b\n" would pass), whereas \z anchors at the true end of the string.

Custom rules

RuleInterface is the package's one extension point: a rule inspects one value and returns an error message when invalid, or null when it passes. The message is the rule's own — there's no separate message subsystem. App-specific rules (e.g. "unique in the database") are application policy and live in the app.

final class Unique implements RuleInterface
{
    public function __construct(private UserRepository $users) {}

    public function validate(mixed $value): ?string
    {
        return $this->users->existsByEmail((string) $value) ? 'Already taken.' : null;
    }
}