Doctrine join entities - php

Question

I'm trying to make some efficient improvements when querying for an entity which has a relationship to another entity.
Entity A:
/**
* #var integer
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
* #var string
* #ORM\Column(name="name", type="string", length=225)
* #Assert\NotBlank(message="Please enter a name for your profile.")
*/
protected $display_name;
/**
* #ORM\OneToOne(targetEntity="Posts", mappedBy="profile", cascade={"all"}, fetch="LAZY")
*/
protected $posts;
Entity B:
/**
* #var integer
* #ORM\Column(name="profile_id", type="integer")
* #ORM\Id
*/
protected $profile_id;
/**
* #ORM\OneToOne(targetEntity="Profile", inversedBy="posts")
* #ORM\JoinColumn(name="profile_id", referencedColumnName="id")
*/
protected $profile;
/**
* #var string
* #ORM\Column(name="content", type="string")
*/
protected $content;
When I count the number of queries being executed I get two, I guess being doctrine runs two separate queries for each entity even through they have a relationship.
I am currently fetching entity A like so:
public function fetchById($id)
{
return $this->createQueryBuilder('p')
->where('p.id = :id')
->setParameter('id', $id)
->getQuery()
->getOneOrNullResult();
}
And then calling entity B like so:
$profile = $profileRepository->fetchById($user->getUserId());
$lastpost = $profile->getPosts()[0];
But I want to be able to join the second entity in this query so that I can just call one query rather than two. I was hoping to do something like this:
public function fetchById($id)
{
return $this->createQueryBuilder('p')
->select('p','pp')
->leftJoin(Posts::class, 'pp', \Doctrine\ORM\Query\Expr\Join::WITH, 'p.id = pp.profile_id')
->where('p.id = :id')
->setParameter('id', $id)
->getQuery()
->getResults();
}
However the left join returns an array of two entities. This is not what I am wanting, because I want to still be able to call for example the getPosts() method in entity A.
I essentially want to populate entity A, including all the related entities. But by only executing one query rather than two, is this possible in doctrine?

Answer 1

Some time ago I had a similar scenario (not with 1-1 but 1-n though), which I solved like this:
// ...Repository
public function findAllForUserWithAll(\AppBundle\Entity\User $u)
{
$query = $this->getEntityManager()->createQueryBuilder('ca1')
->add('select', 'c, s, i, m')
->add('from', 'AppBundle:Contact c')
->leftJoin('c.skills', 's')
->leftJoin('c.interests', 'i')
->leftJoin('c.metAt', 'm')
->where('c.user = :user')
->orderBy('c.lastname', 'ASC')
->setParameters([
'user' => $u,
])
->getQuery();
return $query->getResult();
}
This was in Symfony 2.8.* with Doctrine ^2.4.8 - and the result is one query with 3 joins (instead of 4 queries). Probably not the best code and honestly all the magic happened under the hood. Also your code looks alot alike. But maybe this is expected due to fetch="LAZY" (on entity A) - which my entity does not have?