CASTING attributes for Ordering on a Doctrine2 DQL Query

I am trying to get Doctrine2 Entities, ordered by their ID which apparently is a String even though it contains only Numbers. So what I would like to do is something like this:

SELECT entity1, cast (entity1.id AS integer) AS orderId
FROM Namespace\Bla\MyEntity 
ORDER BY orderId

Is there a way to do something like this in Doctrine2? Or, what would be the best practise to get my Result if i can't change the type of the id (due to customer requirements of course)?

Attention: I am not asking SQL Code, i am asking for a Doctrine2 Solution, preferably in DQL

You should be able to add your own function to implement this feature.

The class would look something like this:

namespace MyProject\Query;

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

class CastAsInteger extends FunctionNode
{
    public $stringPrimary;

    public function getSql(SqlWalker $sqlWalker)
    {
        return 'CAST(' . $this->stringPrimary->dispatch($sqlWalker) . ' AS integer)';
    }

    public function parse(Parser $parser)
    {
        $parser->match(Lexer::T_IDENTIFIER);
        $parser->match(Lexer::T_OPEN_PARENTHESIS);

        $this->stringPrimary = $parser->StringPrimary();

        $parser->match(Lexer::T_CLOSE_PARENTHESIS);
    }
}

You'll need to register your function:

$config = $em->getConfiguration();
$config->addCustomNumericFunction('INT', CastAsInteger::class);

Then you can use it:

SELECT e, INT(e.id) AS HIDDEN orderId
FROM Namespace\Bla\MyEntity e
ORDER BY orderId

PS: By adding the HIDDEN keyword, the alias orderId won't be in the results (and is only used for ordering).