Error when use custom DQL function with Doctrine and Symfony2

Question

I use Symfony 2 and the ORM Doctrine. I want to create and register a custom DQL function. In fact, I want to use the SQL function \"CAST\" in my request, like this :

Answer 1

After several search, I have finally found the solution. I had two problems: first my parse function was wrong, second, I called a SQL function in my orderBy (thank you Cerad).

So, here is my correct class:

namespace Ypok\YPoliceBundle\DQL;

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

class CastFunction extends FunctionNode
{
    public $firstDateExpression = null;
    public $unit = null;    

    public function parse(\Doctrine\ORM\Query\Parser $parser)
    {
        $parser->match(Lexer::T_IDENTIFIER);
        $parser->match(Lexer::T_OPEN_PARENTHESIS);
        $this->firstDateExpression = $parser->StringPrimary();

        $parser->match(Lexer::T_AS);

        $parser->match(Lexer::T_IDENTIFIER);
        $lexer = $parser->getLexer();
        $this->unit = $lexer->token['value'];

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

    public function getSql(\Doctrine\ORM\Query\SqlWalker $sqlWalker)
    {
        return sprintf('CAST(%s AS %s)',  $this->firstDateExpression->dispatch($sqlWalker), $this->unit);
    }
}

And now, I can use perfectly the SQL function 'CAST' in my repository:

$qb = $this->_em->createQueryBuilder();
$qb->select('d, CAST(d.myField AS UNSIGNED) AS sortx')
   ->from('\Test\MyBundle\Entity\MyEntity', 'd')
   ->orderBy('sortx', 'ASC')

return $qb->getQuery()->getResult();

Best regards