How to get a one-dimensional scalar array as a doctrine dql query result?
PhpDoctrine OrmPhp Problem Overview
I want to get an array of values from the id column of the Auction table. If this was a raw SQL I would write:
SELECT id FROM auction
But when I do this in Doctrine and execute:
$em->createQuery("SELECT a.id FROM Auction a")->getScalarResult();
I get an array like this:
array(
array('id' => 1),
array('id' => 2),
)
Instead, i'd like to get an array like this:
array(
1,
2
)
How can I do that using Doctrine?
Php Solutions
Solution 1 - Php
PHP < 5.5
You can use array_map, and since you only have on item per array, you can elegantly use
'current' as callback, instead of writing a closure.
$result = $em->createQuery("SELECT a.id FROM Auction a")->getScalarResult();
$ids = array_map('current', $result);
> See Petr Sobotka's answer below for additional info regarding memory usage.
PHP >= 5.5
As jcbwlkr's answered below, the recommended way it to use array_column.
Solution 2 - Php
As of PHP 5.5 you can use array_column to solve this
$result = $em->createQuery("SELECT a.id FROM Auction a")->getScalarResult();
$ids = array_column($result, "id");
Solution 3 - Php
A better solution is to use PDO:FETCH_COLUMN . To do so you need a custom hydrator:
//MyProject/Hydrators/ColumnHydrator.php
namespace DoctrineExtensions\Hydrators\Mysql;
use Doctrine\ORM\Internal\Hydration\AbstractHydrator, PDO;
class ColumnHydrator extends AbstractHydrator
{
protected function hydrateAllData()
{
return $this->_stmt->fetchAll(PDO::FETCH_COLUMN);
}
}
Add it to Doctrine:
$em->getConfiguration()->addCustomHydrationMode('COLUMN_HYDRATOR', 'MyProject\Hydrators\ColumnHydrator');
And you can use it like this:
$em->createQuery("SELECT a.id FROM Auction a")->getResult("COLUMN_HYDRATOR");
Solution 4 - Php
Ascarius' answer is elegant, but beware of memory usage! array_map() creates a copy of passed array and effectively doubles memory usage. If you work with hundreds of thousands of array items this can become an issue. Since PHP 5.4 call-time pass by reference has been removed so you cannot do
// note the ampersand
$ids = array_map('current', &$result);
In that case you can go with obvious
$ids = array();
foreach($result as $item) {
$ids[] = $item['id'];
}
Solution 5 - Php
Since doctrine/orm 2.10.0 there is a built-in solution for this, see https://www.doctrine-project.org/projects/doctrine-orm/en/2.10/reference/dql-doctrine-query-language.html#scalar-column-hydration
use Doctrine\ORM\AbstractQuery;
$query = $em->createQuery("SELECT a.id FROM Auction a");
return $query->getSingleColumnResult();
// Same as:
return $query->getResult(AbstractQuery::HYDRATE_SCALAR_COLUMN);
Solution 6 - Php
I think it's impossible in Doctrine. Just transform result array into the data structure you want using PHP:
$transform = function($item) {
return $item['id'];
};
$result = array_map($transform, $em->createQuery("SELECT a.id FROM Auction a")->getScalarResult());