Field and API errors

Use a standalone Rule when a value does not need a registered DTO. validate() returns the first error. validateAll() returns every applicable error from the same pipeline.

First error

use Fynix\Rule;

$error = Rule::string('displayName')
    ->min(3)
    ->max(80)
    ->validate('A');

Returned value:

$error->toArray();

[
    'field' => 'displayName',
    'code' => 'length.min',
    'message' => 'Display Name is too short. This field must be at least 3 characters.',
    'parameters' => ['min' => 3],
]

All applicable errors

Password rules are a good use case for validateAll() because a user benefits from seeing the complete policy checklist:

use Fynix\Rule;

$errors = Rule::password('password')
    ->length(12, 128)
    ->validateAll('abc');

$result = array_map(
    static fn ($error): array => $error->toArray(),
    $errors,
);

Representative result:

[
    [
        'field' => 'password',
        'code' => 'length.min',
        'message' => 'Password is too short. This field must be at least 12 characters.',
        'parameters' => ['min' => 12],
    ],
    [
        'field' => 'password',
        'code' => 'password.uppercase',
        'message' => 'Password must contain at least one uppercase letter.',
        'parameters' => [],
    ],
    [
        'field' => 'password',
        'code' => 'password.lowercase',
        'message' => 'Password must contain at least one lowercase letter.',
        'parameters' => [],
    ],
    [
        'field' => 'password',
        'code' => 'password.number',
        'message' => 'Password must contain at least one number.',
        'parameters' => [],
    ],
    [
        'field' => 'password',
        'code' => 'password.special',
        'message' => 'Password must contain at least one special character.',
        'parameters' => [],
    ],
]

When the object is the boundary

For a complete DTO, use the handler instead of manually combining field results:

$errors = ValidationHandler::validate(
    $registration,
    flattenErrorToString: false,
);

That keeps nested traversal, registry resolution, and error formatting in one place.