如何使用doctrine/postgresql [symfony]获取随机元素

Question

我在 postgresql 上配置了一个 symfony/doctrine 项目，我想获得表中某个元素的随机结果。我怎样才能做到这一点？

Answer 1

<?php

// App/Doctrine/DBAL/FunctionNode/Random.php

namespace App\Doctrine\DBAL\FunctionNode;

use Doctrine\ORM\Query\AST\Functions\FunctionNode;
use Doctrine\ORM\Query\Lexer;

/**
 * RandFunction ::= "RANDOM" "(" ")".
 */
final class Random extends FunctionNode
{
    public function parse(\Doctrine\ORM\Query\Parser $parser): void
    {
        $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): string
    {
        return 'RANDOM()';
    }
}

# config/packages/doctrine.yaml
doctrine:
    # ...
    orm:
        dql:
            numeric_functions:
                Random: App\Doctrine\DBAL\FunctionNode\Random

使用示例

<?php

// App\Repository\EntityRepository.php

namespace App\Repository;

class EntityRepository extends ServiceEntityRepository
{
    // ...
    public function getOneRandom()
    {
        return = $this->createQueryBuilder('alias')
            ->orderBy('RANDOM()')
            ->setMaxResults(1)
            ->getQuery()
            ->getOneOrNullResult()
        ;
    }
}

Answer 2

<?php

    namespace App\DQL;

    use Doctrine\ORM\Query\Parser;
    use Doctrine\ORM\Query\SqlWalker;
    use Doctrine\ORM\Query\TokenType;
    use Doctrine\ORM\Query\AST\Functions\FunctionNode;

    class RandomFunction extends FunctionNode {
        /**
         * @param \Doctrine\ORM\Query\Parser $parser
         *
         * @return void
         * @throws \Doctrine\ORM\Query\QueryException
         */
        final public function parse(Parser $parser): void {
            $parser->match(TokenType::T_IDENTIFIER);
            $parser->match(TokenType::T_OPEN_PARENTHESIS);
            $parser->match(TokenType::T_CLOSE_PARENTHESIS);
        }

        final public function getSql(SqlWalker $sqlWalker): string {
            return 'RANDOM()';
        }
    }

# config/packages/doctrine.yaml
doctrine:
        dql :
            numeric_functions:
                Random: App\DQL\RandomFunction