symfony - custom query in entity field type

Question

I build a form with entity type like this:

$form = $this->createFormBuilder()
->add('users', 'entity', array(
    'class' => 'UserBundle:Users',
        'query_builder' => function(EntityRepository $er) {
            return $er->createQueryBuilder('u')
                          ->orderBy('u.name', 'ASC');
                        },)
      )
->getForm();

Now I want to modify this form, to show only distinct users. I try this:

->add('users', 'entity', array(
                        'class' => 'UserBundle:Users',
                        'query_builder' => function(EntityRepository $er) {
                        return $er->createQuery('SELECT DISTINCT u.name FROM UserBundle:Users ORDER BY u.name ASC')->getResult();
                        },)
                      )

but Symfony throws me an exception. My question is how can I use custom query in entity field type?

---

I don't understand what you mean with last answer. My code looks like:

repository:

public function getDistinctUsers()
{
    return $this->getEntityManager()->createQuery('SELECT DISTINCT u.name FROM UserBundle:Users u ORDER BY u.name DESC')->getResult();
}

controller:

->add('users', 'entity', array(
    'class' => 'UserBundle:Users',
    'query_builder' => function(EntityRepository $er) {
            return $er->getDistinctUsers();
         },)
      )

twig:

<form action="{{ path('user') }}" method="post" {{ form_enctype(form) }}>
    {{ form_widget(form) }}
    <input type="submit" />
</form>

and it throws an exception: An exception has been thrown during the rendering of a template ("Expected argument of type "DoctrineORMQueryBuilder", "array" given") ...

Answer 1

The easiest way is to add a group by in the query:

$form = $this->createFormBuilder()
  ->add('users', 'entity', array(
    'class' => 'UserBundle:Users',
    'query_builder' => function(EntityRepository $er) {
      return $er->createQueryBuilder('u')
                ->groupBy('u.id')
                ->orderBy('u.name', 'ASC');
      },)
    )
->getForm();