---
title: "Certificate Validator"
description: "What the CertificateValidator checks, how to make it check the format of the ID with a regular expression and how to write your own validator"
type: "docs"
category: "doc"
tags: []
authors: [Anonymous]
date: "2026-10-17"
last_update: "2026-10-17"
time_minutes: 2
draft: false
unlisted: false
url: "https://www.derafu.dev/docs/data/certificate/certificate-validator"
---

# CertificateValidator Class

`CertificateValidator::validate()` checks that a certificate can be used. It returns nothing if it can, and throws a `CertificateException` if it can not.

```php
use Derafu\Certificate\Service\CertificateValidator;

$validator = new CertificateValidator();
$validator->validate($certificate);
```

## What It Checks

In this order:

1. The certificate has an ID (`getId()`; if it has none, the exception of `getId()` is the one that is thrown).
2. The ID matches the format that you gave to the validator, if you gave one.
3. The certificate is not expired.

Without a format, any ID is valid: the validator does not know what an ID should look like, because that depends on who issues the certificates.

## The Format of the ID

The format is a regular expression, with its delimiters, that the validator receives when it is created:

```php
// The ID is digits, a dash and a check character that is a digit or an uppercase "K".
$validator = new CertificateValidator('/^\d+-[\dK]$/');

$validator->validate($certificate); // "11222333-9" or "10-K": valid.
                                    // "10-k", "123" or "abc-9": it throws.
```

When the ID does not match, the message says the ID and the format:

```
The ID 10-k of the certificate does not match the format /^\d+-[\dK]$/.
```

The validator checks the ID as it is in the certificate (`getId(forceUpper: false)`), so a format that requires uppercase works.

If the regular expression is not valid, the validator throws a `CertificateException` when it is created, not when it validates.

## Using It with the Service

`CertificateService` receives the validator, so the format is set where the validator is created:

```php
$service = new CertificateService(
    $faker,
    $loader,
    new CertificateValidator('/^\d+-[\dK]$/')
);

$service->validate($certificate);
```

In an application with the Symfony container, the validator is registered in `resources/config/certificate-services.yaml` of the library without a format. To use one, declare the argument of the service in your own configuration.

## Your Own Validator

For other validations, implement `CertificateValidatorInterface` (see [Certificate Service](certificate-service)).



---
Last updated on 17/10/2026