Doctrine CreateQueryBuilder returns repeated result - doctrine-orm

Question

In Symfony3 I'm running
php app/console generate:doctrine:entity --entity=AcmeBlogBundle:Post
It creates 2 files: Post (in entity folder) and PostRepository (in repository folder extending \Doctrine\ORM\EntityRepository)
Everything is fine until I try to run the following repository-custom-function in my controller
$rir = $this->getDoctrine()->getRepository("AcmeBlogBundle:Post");
$replacementInstruction = $rir->getOneBy(
array("id" => 6)
);
My custom repository function is as follow
public function getOneBy($option)
{
$alias = "p";
$fields = $this->prepareRequestSelectFields("p");
$qb = $this->createQueryBuilder('Post');
$qb->select($fields)
->from('AcmeBlogBundle:Post', $alias)
->where($alias . '.id = :id')
->setParameter('id', 6)
;
$result = $qb->getQuery()->getResult();
}
private function prepareRequestSelectFields($alias)
{
return $alias. ".id";
}
In my database there are 10 posts with id from 1 to 10, so I expect it to return 1 result, however it return correct Post (id 6) 10 times
Why is that?
p.s. if I move the query builder to a custom service wrapper e.g. PostManager it works just fine (returning 1)

Answer 1

This doesn't really answer my question but apparently createQueryBuilder() in EntityRepository and in EntityManager are different, thanks to https://maltronic.io/2014/12/22/doctrine-createquerybuilder-entitymanager-vs-entityrepository/
So in my EntityRepository it should be
...
$qb = $this->createQueryBuilder('p'); // this should be the alias
$qb->select($fields)
// ->from('AcmeBlogBundle:Post', $alias) // remove this
->where($alias . '.id = :id')
->setParameter('id', 6)
;
...
Personally I dislike how 2 different functions has the same name, but I guess it's fine because one is from Doctrine and one is from Symfony. They are decoupled
edit Actually I might be wrong, they are both from Doctrine ... sigh
Still tho, it doesn't answer why in my original code, it returns multiple time

Answer 2

What about getSingleResult() rather than getResult() ? And you should maybe use the doctrine method findOneBy()

Answer 3

You can use the helper methods provided by the repositories, allowing you to fetch one or multiples entities from repositories with dynamic method names, in your case you want to fetch one post by id:
//fetch one
$replacementInstruction = $this->getDoctrine()->getRepository("AcmeBlogBundle:Post")->findOneById(6);
For information, fetching all entities is done with ->findByProperty