Doctrine2 apply function to query parameter - doctrine-orm

Question

I use the doctrine query builder to build my query.
$qb = $this->getEntityManager()->createQueryBuilder();
$qb->select(array('u'))->from('Account', 'a');
-- problem here
$qb->where('lower_unaccent(u.email) LIKE :search');
$qb->setParameter('search', $search['search'] . '%');
This works fine, but I would also like to apply the lower_unaccent function to the search parameter.
Is there a way to do this with the query builder?
Because when I do LOWER_UNACCENT(u.email) LIKE LOWER_UNACCENT(:search) I get the following error:
Error: Expected Doctrine\ORM\Query\Lexer::T_STRING, got 'LOWER_UNACCENT'
Even if I change LOWER_UNACCENT TO LOWER, I get the same error message.

Answer 1

You have to use $qb->expr()->lower('u.email') and $qb->expr()->lower(':search'). To create the "LIKE" pass those as arguments to $qb->expr()->like().
There doesn't seem to be a unaccent method though, but maybe there is a way to customize this. Let me know how it went.
EDIT:
Looking into lower()'s code, it seems like you can use any function you want like this:
new Expr\Func('LOWER', array($x));

Answer 2

By default, I'm pretty sure you can't do that.
lower_unaccent is not standard SQL, and as far as I can see, not supported by Doctrine.
What you can do is extend DQL with user-defined functions, which will do whatever you want. It is not so hard to implement. Here is some documentation:
http://docs.doctrine-project.org/en/2.0.x/cookbook/dql-user-defined-functions.html
http://docs.doctrine-project.org/en/2.0.x/reference/dql-doctrine-query-language.html#adding-your-own-functions-to-the-dql-language