How to select randomly with doctrine

Question

Here is how I query my database for some words

$query = $qb->select(\'w\')
    ->from(\'DbEntities\\Entity\\Word\', \'w\')
    ->where(\'w.indiction         


        

Answer 1

Just add the following:

->orderBy('RAND()')

Answer 2

@Krzysztof's solution is IMHO best here, but RAND() is very slow on large queries, so i updated @Krysztof's solution to gives less "random" results, but they are still random enough. Inspired by this answer https://stackoverflow.com/a/4329492/839434.

namespace Project\ProductsBundle\Entity;

use Doctrine\ORM;

class ProductRepository extends ORM\EntityRepository
{
    /**
     * @param int $amount
     * @return Product[]
     */
    public function getRandomProducts($amount = 7)
    {
        return $this->getRandomProductsNativeQuery($amount)->getResult();
    }

    /**
     * @param int $amount
     * @return ORM\NativeQuery
     */
    public function getRandomProductsNativeQuery($amount = 7)
    {
        # set entity name
        $table = $this->getClassMetadata()
            ->getTableName();

        # create rsm object
        $rsm = new ORM\Query\ResultSetMapping();
        $rsm->addEntityResult($this->getEntityName(), 'p');
        $rsm->addFieldResult('p', 'id', 'id');

        # sql query
        $sql = "
            SELECT * FROM {$table}
            WHERE id >= FLOOR(1 + RAND()*(
                SELECT MAX(id) FROM {$table})
            ) 
            LIMIT ?
        ";

        # make query
        return $this->getEntityManager()
            ->createNativeQuery($sql, $rsm)
            ->setParameter(1, $amount);
    }
}

Answer 3

I hope this would help others:

        $limit = $editForm->get('numberOfQuestions')->getData();
        $sql = "Select * from question order by RAND() limit $limit";

        $statement = $em->getConnection()->prepare($sql);
        $statement->execute();
        $questions = $statement->fetchAll();

Note here the table question is an AppBundle:Question Entity. Change the details accordingly. The number of questions is taken from the edit form, make sure to check the variable for the form builder and use accordingly.

Answer 4

I know this is an old question. But I used the following solution to get the random row.

Using an EntityRepository method:

public function findOneRandom()
{
    $id_limits = $this->createQueryBuilder('entity')
        ->select('MIN(entity.id)', 'MAX(entity.id)')
        ->getQuery()
        ->getOneOrNullResult();
    $random_possible_id = rand($id_limits[1], $id_limits[2]);

    return $this->createQueryBuilder('entity')
        ->where('entity.id >= :random_id')
        ->setParameter('random_id', $random_possible_id)
        ->setMaxResults(1)
        ->getQuery()
        ->getOneOrNullResult();
}

Answer 5

Probably the easiest (but not necessarily the smartest) way to get a single object result ASAP would be implementing this in your Repository class:

public function findOneRandom()
{
    $className = $this->getClassMetadata()->getName();

    $counter = (int) $this->getEntityManager()->createQuery("SELECT COUNT(c) FROM {$className} c")->getSingleScalarResult();

    return $this->getEntityManager()

        ->createQuery("SELECT ent FROM {$className} ent ORDER BY ent.id ASC")
        ->setMaxResults(1)
        ->setFirstResult(mt_rand(0, $counter - 1))
        ->getSingleResult()
    ;
}

Answer 6

The Doctrine team is not willing to implement this feature.

There are several solutions to your problem, each having its own drawbacks:

• Add a custom numeric function: see this DQL RAND() function
  (might be slow if you have lots of matching rows)
• Use a native query
  (I personally try to avoid this solution, which I found hard to maintain)
• Issue a raw SQL query first to get some IDs randomly, then use the DQL WHERE x.id IN(?) to load the associated objects, by passing the array of IDs as a parameter.
  This solution involves two separate queries, but might give better performance than the first solution (other raw SQL techniques than ORDER BY RAND() exist, I won't detail them here, you'll find some good resources on this website).