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

Why not to use repository?

<?php

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');

        # make query
        return $this->getEntityManager()->createNativeQuery("
            SELECT p.id FROM {$table} p ORDER BY RAND() LIMIT 0, {$amount}
        ", $rsm);
    }
}

Answer 2

For me, the most useful way was to create two arrays where i say order type and different properties of the Entity. For example:

    $order = array_rand(array(
        'DESC' => 'DESC',
        'ASC' => 'ASC'
    ));

    $column = array_rand(array(
        'w.id' => 'w.id',
        'w.date' => 'w.date',
        'w.name' => 'w.name'
    ));

You could add more entries to array $column like criteria.

Afterwards, you can build your query with Doctrine adding $column and $order inside ->orderBy. For example:

$query = $qb->select('w')
->from('DbEntities\Entity\Word', 'w')
->where('w.indictionary = 0 AND w.frequency > 3')
->orderBy($column, $order)
->getQuery()
->setMaxResults(100);

This way improved the performance of my application. I hope this helps someone.

Answer 3

Follow these steps:

Define a new class at your project as:

namespace My\Custom\Doctrine2\Function;

use Doctrine\ORM\Query\Lexer;

class Rand extends \Doctrine\ORM\Query\AST\Functions\FunctionNode
{

    public function parse(\Doctrine\ORM\Query\Parser $parser)
    {
        $parser->match(Lexer::T_IDENTIFIER);
        $parser->match(Lexer::T_OPEN_PARENTHESIS);
        $parser->match(Lexer::T_CLOSE_PARENTHESIS);
    }

    public function getSql(\Doctrine\ORM\Query\SqlWalker $sqlWalker)
    {
        return 'RAND()';
    }
}

Register the class config.yml:

doctrine:
     orm:
         dql:
             numeric_functions:
                 Rand: My\Custom\Doctrine2\Function\Rand

Use it directly as:

$qb->addSelect('RAND() as HIDDEN rand')->orderBy('rand()'); //Missing curly brackets

Answer 4

Or you could do this -->

$words = $em->getRepository('Entity\Word')->findAll();
shuffle($words);

Of course this would be very inefficient if you have many records so use with caution.

Answer 5

First get the MAX value from DB table & then use this as offset in PHP i.e $offset = mt_rand(1, $maxId)

Answer 6

In line with what Hassan Magdy Saad suggested, you can use the popular DoctrineExtensions library:

See mysql implementation here: https://github.com/beberlei/DoctrineExtensions/blob/master/src/Query/Mysql/Rand.php

# config.yml

doctrine:
     orm:
         dql:
             numeric_functions:
                 rand: DoctrineExtensions\Query\Mysql\Rand

Tested in Doctrine ORM 2.6.x-dev, you can then actually do:

->orderBy('RAND()')