Question

Is it safe to change name of database column on the fly in Doctrine’s mapping in application’s bootstrap in case I will do it for all created entity managers?

<?php
// In "every second" view sort by score2 instead of by score1 
if (rand(0, 1) % 2 === 0) {
   $entityManager->getMetadataFactory()->getMetadataFor('Advertisement')->fieldMappings['score']['columnName'] = 'score2';
}

Score attribute is used for sorting of displayed entities and I would like to do A/B testing of sorting by different database columns in the easiest way.

Answer 1

Ok so it seems I have solution.

The best way is probably to make own ClassMetadataFactory which is extended from \Doctrine\ORM\Mapping\ClassMetadataFactory and create EntityManagers with this ClassMetadataFactory.

<?php
/**
 * Implementation of Doctrine's metadata factory class for A/B testing
 */
class ClassMetadataFactory extends \Doctrine\ORM\Mapping\ClassMetadataFactory
{
    /**
     * Gets the class metadata descriptor for a class.
     *  
     * @param string $className The name of the class.
     * @return Doctrine\ORM\Mapping\ClassMetadata
     */
    public function getMetadataFor($className)
    {
        $metadata = parent::getMetadataFor($className);

        if ($className === 'Advertisement' || $className === '\Advertisement') {
            $metadata->fieldMappings['score']['columnName'] = 'score2';
            $metadata->fieldNames['score'] = 'score2';
            $metadata->columnNames['score'] = 'score2';
        }

        return $metadata;
    }
}

Another thing you should be aware of is Doctrine’s DQL cache!

This is relative silly example. Next step could be to do configuration of A/B testing and some switch responsible for variant decision, but this is out of topic my question above.