Icinga PHP Library - Common Validators and Validator Chaining

ipl/validator provides a collection of reusable input validators and a ValidatorChain to compose and execute multiple validators in a user-defined order.

Installation

The recommended way to install this library is via Composer:

composer require ipl/validator

ipl/validator requires PHP 8.0 or later with the mbstring and openssl extensions.

Usage

Applying a Single Validator

Every validator exposes the same basic workflow:

1. Configure the validator
2. Call isValid($value)
3. Read validation errors via getMessages() if validation fails

use ipl\Validator\StringLengthValidator;

$validator = new StringLengthValidator([
    'min' => 3,
    'max' => 10,
]);

// $value is the input to validate.
if (! $validator->isValid($value)) {
    echo implode(PHP_EOL, $validator->getMessages());
}

Composing Multiple Validators with ValidatorChain

Use ValidatorChain when a value must satisfy multiple conditions. By default, all validators run in sequence even when one fails, so every error is collected. Set breakChainOnFailure: true when adding a validator to stop on the first failure.

use ipl\Validator\HostnameValidator;
use ipl\Validator\RegexMatchValidator;
use ipl\Validator\ValidatorChain;

$chain = new ValidatorChain();
$chain->add(new HostnameValidator(), breakChainOnFailure: true);
$chain->add(new RegexMatchValidator('/^api\./'));

// $value is the input to validate.
if (! $chain->isValid($value)) {
    echo implode(PHP_EOL, $chain->getMessages());
}

In this example, the chain stops early when HostnameValidator fails because it was added with breakChainOnFailure: true.

Built-In Validators

ipl/validator ships with validators for common categories of input:

• Value and range — string length, numeric comparisons, and membership tests

• Text and network formats — email addresses, hostnames, CIDR notation, dates, and regular expressions

• File and security — uploaded files, private keys, and X.509 certificates

• Custom logic — callback-based validation for specific rules:

  use ipl\Validator\CallbackValidator;
  
  // Illustrates cross-field validation, omits type checks for brevity.
  $validator = new CallbackValidator(function ($end, CallbackValidator $validator) use ($start): bool {
      if ($end <= $start) {
          $validator->addMessage('End must be after start.');
  
          return false;
      }
  
      return true;
  });

  Use this for rules that built-in validators cannot express — such as cross-field comparisons or checks against runtime state.

Changelog

See CHANGELOG.md for a list of notable changes.

License

ipl/validator is licensed under the terms of the MIT License.