How to get Array Results in findAll() - Doctrine?

It's possible to use $query->getArrayResult() as a shortcut to $query->getResult(Query::HYDRATE_ARRAY)

doctrine hydration modes

The findAll() method does not have any parameters. You can, for example, use the repository's createQueryBuilder() method to achieve what you want to do:

use Doctrine\ORM\Query;

// ...

$query = $this->getDoctrine()
    ->getRepository('CoreBundle:Categories')
    ->createQueryBuilder('c')
    ->getQuery();
$result = $query->getResult(Query::HYDRATE_ARRAY);