repository.php

<?php
        $resultSetMapping = new ResultSetMapping();
        $resultSetMapping->addEntityResult('MyAppBundle:Phone', 'p');
        $resultSetMapping->addFieldResult('p', 'id', 'id');
        $resultSetMapping->addFieldResult('p', 'master_id', 'masterId');
        $resultSetMapping->addFieldResult('p', 'slug', 'slug');
        $resultSetMapping->addFieldResult('p', 'price', 'price');
        $resultSetMapping->addFieldResult('p', 'name', 'name');

        $query = $this->getEntityManager()->createNativeQuery('
            SELECT * FROM
                (
                    SELECT * FROM Phone
                    ORDER BY price ASC
                ) AS Phones
            GROUP BY Phones.master_id
            ORDER BY Phones.displayOrder
        ', $resultSetMapping);

        return $query->getResult();

/* Is there a better way to achieve that with doctrine? Here's the plain sql query: */
SELECT * FROM (SELECT * FROM Phone ORDER BY price ASC) AS Phones GROUP BY Phones.master_id ORDER BY Phones.displayOrder;