Fetch multi-row, single-column array using Doctrine

Question

I have a Doctrine fetch statement like this

$query = "SELECT id FROM table LIMIT 2";
$result = $db->fetchAll($query);

which returns the array like this:

Array
(
[0] => Array
    (
        [id] => 1
    )

[1] => Array
    (
        [id] => 2
    )
)

Since the only column I fetch is ID, I don't need the array scope do be that deep. Is there a convenient way of making Doctrine return the results in a "flat" array, similar to what what PDO does:

$result = $db->query($query)->fetchAll(PDO::FETCH_COLUMN);

will return

Array
(
    [0] => 1
    [1] => 2
)

Currently I am flattening it using

$result = call_user_func_array('array_merge', array_map("array_values", $result));

Answer 1

To resolve this problem you have to make your custom doctrine hydrator.

1. First: Make your own hydrator

<?php
namespace MyProject\Hydrators;

use Doctrine\ORM\Internal\Hydration\AbstractHydrator;

class CustomHydrator extends AbstractHydrator
{
    protected function _hydrateAll()
    {
        return $this->_stmt->fetchAll(PDO::FETCH_COLUMN);
    }
}

2. Add your hydrator to Doctrine configuration file :

<?php
$em->getConfiguration()->addCustomHydrationMode('CustomHydrator','MyProject\Hydrators\CustomHydrator');

3. Finaly you can use your cutom hidrator :

<?php
$query = $em->createQuery('SELECT u FROM CmsUser u');
$results = $query->getResult('CustomHydrator');

Answer 2

I found a method called fetchFirstColumn which appears to do this. This was probably added in a later version of doctrine. I am currently on Doctrine ORM 2.7.4.

I am using it like this in Symfony:

$statement = $connection->prepare('SELECT foo FROM bar WHERE baz = :baz');
$statement->execute([':baz' => 1]);
$result = $statement->fetchFirstColumn();

The value of $result will be a numerically indexed array starting at 0 like this:

[
    0 => 'foo1', 
    1 => 'foo2'
];

Answer 3

You can simply use the PDO functionality (at least if you have MySQL).

$ids = $db
    ->executeQuery($query)
    ->fetchAll(\PDO::FETCH_COLUMN)
;

Answer 4

Fetch the data using fetchAssoc:

$result = $db->query($query)->fetchAssoc(PDO::FETCH_COLUMN);

You will get an Array like this:

Array ( 
    [id] => 11
)