Doctrine2 - How can I order by a discriminator column?

Question

How should I go about ordering by a discriminator column in a doctrine repository query?

I have a pretty straight forward setup, I have different types of payment detai

Answer 1

Can your try to use TYPE() or INSTANCE OF?

related: https://groups.google.com/forum/#!topic/doctrine-user/JtCbwuN-37o

However, this topic doesn't say if it is implemented or not. At the time it was written someone said order by wouldn't work.

$dql = 'SELECT pd
        from
        AccountingBundle:PaymentDetail pd
        JOIN ClientProductBundle:ClientProduct cp
        WITH cp.payment_detail_id = pd.id
        WHERE
        cp.payment_detail_id = pd.id
        and cp.client_contact_id = :client_contact_id
        GROUP BY pd.id
        ORDER BY TYPE(pd)';

Answer 2

Even though TYPE is not implemented yet into the core of doctrine it's still possible to implement it as a custom user function.

Someone already did an amazing job and implemented it for us. Just in case the resource will be removed in the future, here is a slightly adjusted version for php7+:

<?php
use Doctrine\ORM\Mapping\ClassMetadataInfo;
use Doctrine\ORM\Query\AST\Functions\FunctionNode;
use Doctrine\ORM\Query\Lexer;
use Doctrine\ORM\Query\Parser;
use Doctrine\ORM\Query\QueryException;
use Doctrine\ORM\Query\SqlWalker;

class TypeFunction extends FunctionNode
{
    /**
     * @var string
     */
    public $dqlAlias;

    public function getSql(SqlWalker $sqlWalker): string
    {
        /** @var ClassMetadataInfo $class */
        $class = $sqlWalker->getQueryComponent($this->dqlAlias)['metadata'];
        $tableAlias = $sqlWalker->getSQLTableAlias($class->getTableName(), $this->dqlAlias);

        if (!isset($class->discriminatorColumn['name'])) {
            $message = 'TYPE() only supports entities with a discriminator column.';
            throw QueryException::semanticalError($message);
        }

        return $tableAlias . '.' . $class->discriminatorColumn['name'];
    }

    public function parse(Parser $parser)
    {
        $parser->match(Lexer::T_IDENTIFIER);
        $parser->match(Lexer::T_OPEN_PARENTHESIS);
        $this->dqlAlias = $parser->IdentificationVariable();
        $parser->match(Lexer::T_CLOSE_PARENTHESIS);
    }
}

Now you can order by the discriminator column by doing something like:

SELECT e, TYPE(e) AS HIDDEN my_type FROM Entity e ORDER BY my_type DESC;

Answer 3

It seems like the simplest solution (so far) is to add another field to the base class and copy the discriminator column value.

The aforementioned TYPE(q) works only in WHERE clause.