Get access through another Entity in Doctrine2 - doctrine-orm

Question

I have the problem with Association in Doctrine2.
My Entity mapping is:
Brand:
/**
* #ORM\Entity
*/
class Brand
{
/**
* #ORM\Id
*/
protected $id;
/**
* #ORM\Column(type="string")
*/
protected $name;
/**
* #ORM\OneToMany(targetEntity="AppBundle\Entity\Model", mappedBy="brand")
*/
protected $models;
/**
* #ORM\Column(type="boolean")
*/
protected $isPopular;
}
Model:
/**
* #ORM\Entity
*/
class Model
{
/**
* #ORM\Id
*/
protected $id;
/**
* #ORM\Column(type="string")
*/
protected $name;
/**
* #ORM\ManyToOne(targetEntity="AppBundle\Entity\VehicleType", inversedBy="models")
* #ORM\JoinColumn(name="vehicle_type_id", referencedColumnName="id")
*/
protected $vehicleType;
/**
* #ORM\ManyToOne(targetEntity="AppBundle\Entity\Brand", inversedBy="models")
* #ORM\JoinColumn(name="brand_id", referencedColumnName="id")
*/
protected $brand;
}
VehicleType:
/**
* #ORM\Entity
*/
class VehicleType
{
/**
* #ORM\Id
*/
protected $id;
/**
* #ORM\Column(type="string")
*/
protected $name;
/**
* #ORM\OneToMany(targetEntity="AppBundle\Entity\Model", mappedBy="vehicleType")
*/
protected $models;
}
How I can get in Entity VehicleType array of popular Brands (brand.isPopular = true)?
Мay be my mapping is wrong?

Answer 1

I can do like this
$vehicleTypes = $this->getEm()->getRepository('AppBundle:VehicleType')->findAll();
foreach ($vehicleTypes as $vehicleType) {
print ('<p>'.$vehicleType->getName().'</p>');
$brands = $this->getQb()
->select('brand')
->from('AppBundle:Brand', 'brand')
->join('brand.models', 'models')
->where('brand.isPopular = true')
->andWhere('models.vehicleType = :vehicleType')
->setParameter('vehicleType', $vehicleType)
->getQuery()
->getResult()
;
foreach ($brands as $brand) {
print('<p> - '.$brand->getNameEng().'</p>');
}
}
But I have n+1 querys to DB, where n size of VehicleType. Posible decrise DB querys?