Config validation

Drupal's next leap?

Wim Leers
Senior Principal Software Engineer
Acquia logo 's Drupal Acceleration Team

A brief history of config in Drupal
era	storage	blobbiness
2004	`variable` table	extremely	🙈
2012	YAML files	diffable	🤓𝍔
2013	[…] + schema	introspectable	🤔💡
2014	`config` table + […]	unchanged	🏎️
2017	[…] + […] + constraints	validatable	✅

Trend: more structure

introspectable (👋 variable module)
translatable (👋 i18n module)
exportable (👋 ctools exportables)

type: uuid

👆

the only validatable config type

😱

Why?

🤷‍♀️

Writing configuration via JSON:API
Admin UI improvements 🪦 JS Admin UI
Reliable config_split, config_filter …
Recipes Initiative
Automatic Updates Initiative
Ambitious site builder experiences

There are many capabilities blocked on this. It's not just that this blocks writing configuration via JSON:API, which in turn blocked the JS Admin UI initiative which has since stopped. It's also that it is impossible to reuse the same validation logic for the JS admin UI: it literally needs to be re-implemented, which is a big security risk. If we move the current logic out of forms, we benefit multiple times: custom admin UIs (on the server or client) become possible, UIs become simpler to maintain, additional validation (from a contrib or custom module) becomes easy to add, et cetera. Talking to Fabian Bircher, maintainer of https://www.drupal.org/project/config_split and https://www.drupal.org/project/config_filter, he said a key problem is to know if a key is required or not. Sometimes when a value is null or the array empty we can omit the key and sometimes not. These are problems that are easily solvable with validation.

Config schema 101

📚

type: uuid use

config_entity:
  type: mapping
  mapping:
    uuid:
      type: uuid
      label: 'UUID'
  …

type: uuid definition

# A UUID.
uuid:
  type: string
  label: 'UUID'
  constraints:
    Uuid: {}

core/config/schema/core.data_types.schema.yml

"Uuid" 👉 a @Constraint plugin ID

namespace Drupal\Core\Validation\Plugin\Validation\Constraint;

use Symfony\Component\Validator\Constraints\Uuid;
use Symfony\Component\Validator\Constraints\UuidValidator;

/**
 * Validates a UUID.
 *
 * @Constraint(
 *   id = "Uuid",
 *   label = @Translation("Universally Unique Identifier", context = "Validation"),
 * )
 */
class UuidConstraint extends Uuid {

  /**
   * {@inheritdoc}
   */
  public function validatedBy() {
    return UuidValidator::class;
  }

  public $message = 'This is not a valid UUID.';

}

namespace Symfony\Component\Validator\Constraints;

class UuidValidator extends ConstraintValidator {

    public function validate(mixed $value, Constraint $constraint) {
        if (!$constraint instanceof Uuid) {
            throw new UnexpectedTypeException($constraint, Uuid::class);
        }
        if (!\is_scalar($value) && !$value instanceof \Stringable) {
            throw new UnexpectedValueException($value, 'string');
        }
        …
    }

}

🧑‍🎓🥳

Live demo #1

d.o/project/config_inspector

drush config:inspect

drush config:inspect --todo

drush config:inspect --filter-keys=node.type.article \
                     --detail \
                     --list-constraints

Live demo #2

Validation constraints in forms

Implement ConfigFormBase's optional methods since Drupal 10.2: #3373502
💰🌈

Implement ConfigFormBase's optional methods since Drupal 10.2: #3373502
💰🌈
Optional: ConfigEvents::SAVE subscriber to validate your config
🥳🥇

🙏

Joris Vercammen aka @borisson_ — Calibrate
Adam Hoenich aka @phenaproxima — Acquia
Ben Mullins aka @bnjmnm — Acquia
Fabian Bircher aka @bircher — Nuvole
Daniel Wehner aka @dawehner ^(2018!)
Alex Pott aka @alexpott ^{(2018–now!)}

🙇🏻‍♂️

META	#2164373 👀 ⤵
🟢 Required values	#3364109
🟡 Required keys	#3364108
🚢 ~~Validate in tests~~	#3361534

Which config changes have caused outages for YOU? 🫵