DQL join two joined tables from different tables - doctrine

Question

I know the title isn't very clear, but I will try to better explain my problem here.
I have 3 Doctrine entities : A, B and C
class A { class B { class C {
$id; $id; $id;
ManyToMany ManyToMany }
$C; $C;
} }
I'm trying to know if an object A and an object B have at least one same C.
The many to many relations gives me table like :
table AC { table BC {
A_id; B_id;
C_id; C_id;
} }
I know that I can't use these tables in DQL but what I want to do can be done in SQL. It would give :
SELECT COUNT(A.id) FROM AC INNER JOIN BC
ON AC.C_id = BC.C_id
WHERE BC.B_id=1217 AND AC.A_id=185

Answer 1

You will need to make the many to many accosiation bidirectional, so entities will look like this:
<?php
namespace App\Model;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Entity
*/
class A
{
/**
* #ORM\Id
* #ORM\Column(type="integer")
* #ORM\GeneratedValue
* #var integer
*/
private $id;
/**
* #var ArrayCollection|C[]
* #ORM\ManyToMany(targetEntity="C", inversedBy="as")
*/
private $cs;
}
/**
* #ORM\Entity
*/
class B
{
/**
* #ORM\Id
* #ORM\Column(type="integer")
* #ORM\GeneratedValue
* #var integer
*/
private $id;
/**
* #var ArrayCollection|C[]
* #ORM\ManyToMany(targetEntity="C", inversedBy="bs")
*/
private $cs;
}
/**
* #ORM\Entity
*/
class C
{
/**
* #ORM\Id
* #ORM\Column(type="integer")
* #ORM\GeneratedValue
* #var integer
*/
private $id;
/**
* #var ArrayCollection|A[]
* #ORM\ManyToMany(targetEntity="A", mappedBy="cs")
*/
private $as;
/**
* #var ArrayCollection|A[]
* #ORM\ManyToMany(targetEntity="B", mappedBy="cs")
*/
private $bs;
}
And then you can query the C class with conditional join on A and B entities, by this DQL query:
$query = $this->entityManager->createQuery("SELECT count(c.id) FROM C::class c INNER JOIN c.as a WITH a.id = :a_id INNER JOIN c.bs b WITH b.id = :b_id")
->setParameter('a_id', 185)
->setParameter('b_id', 1217);
$result = $query->getSingleScalarResult();