Dirty solution to detect changes at columnDefinition

[CheAlex]

Feature Request

Q	A
New Feature	yes
RFC	yes

Summary

Doctrine doesn't detect changes at columnDefinition: https://www.doctrine-project.org/projects/doctrine-orm/en/3.2/reference/attributes-reference.html#column

Dirty solution

Doctrine doesn't detect changes at columnDefinition, but Doctrine detects mapping's changes if comment changed. The solution is to add virtual comment with value based on hash of columnDefinition:

columnDefinition changed -> hash(columnDefinition) changed -> comment changed -> Doctrine detect mapping's changes

Tested example

<?php

declare(strict_types=1);

namespace RootNs\Entity\Attributes;

#[\Attribute(\Attribute::TARGET_PROPERTY)]
final class ColumnDefinitionHashComment
{
}

<?php

declare(strict_types=1);

namespace RootNs\EventListener;

use Doctrine\ORM\Mapping as ORM;
use RootNs\Entity\Attributes\ColumnDefinitionHashComment;

#[ORM\Entity]
#[ORM\Table(name: 'users')]
class User
{
    #[ORM\Id]
    #[ORM\Column(name: 'id', type: 'uuid', unique: true, nullable: false)]
    private UuidInterface $id;

    #[ORM\Column(type: 'json_document', options: [
        'jsonb' => true,
    ])]
    private UserData $data;

    #[ColumnDefinitionHashComment]
    #[ORM\Column(
        type: 'integer',
        nullable: false,
        insertable: false,
        updatable: false,
        columnDefinition: 'INT GENERATED ALWAYS AS (JSON_VALUE(data, "$.id")) NOT NULL',
    )]
    private readonly int $relationId;
}

<?php

declare(strict_types=1);

namespace RootNs\EventListener;

use Doctrine\ORM\Event\LoadClassMetadataEventArgs;
use Doctrine\ORM\Mapping\FieldMapping;
use RootNs\Entity\Attributes\ColumnDefinitionHashComment;
use ReflectionProperty;

class ColumnDefinitionHashCommentSubscriber
{
    public function loadClassMetadata(LoadClassMetadataEventArgs $event): void
    {
        $classMetadata = $event->getClassMetadata();

        foreach ($classMetadata->fieldMappings as $fieldName => $fieldMapping) {
            $reflectionProperty = $classMetadata->reflClass->getProperty($fieldName);
            assert(null !== $reflectionProperty);
            $attributes = $reflectionProperty->getAttributes(ColumnDefinitionHashComment::class);

            if ([] === $attributes) {
                continue;
            }

            $this->addColumnDefinitionCommentHash($classMetadata->getName(), $reflectionProperty, $fieldMapping);
        }
    }

    private function addColumnDefinitionCommentHash(
        string $className,
        ReflectionProperty $reflectionProperty,
        FieldMapping $fieldMapping
    ): void {
        if (null === $fieldMapping->columnDefinition) {
            throw new \LogicException(sprintf(
                'At entity field %s:%s columnDefinition must be defined',
                $className,
                $reflectionProperty->getName()
            ));
        }

        if (false !== strripos($fieldMapping->columnDefinition, 'comment')) {
            throw new \LogicException(sprintf(
                'At entity field %s:%s comment must not be at columnDefinition',
                $className,
                $reflectionProperty->getName()
            ));
        }

        // xxh3 - is the fastest supported algorithm in php: https://php.watch/articles/php-hash-benchmark
        $fieldMapping->options['comment'] = sprintf(
            '(columnDefinitionHash:%s)',
            hash('xxh3', $fieldMapping->columnDefinition)
        );
        $fieldMapping->columnDefinition .= sprintf(' COMMENT "%s"', $fieldMapping->options['comment']);
    }
}