Weird Doctrine ODM exception when using references together with inheritance - symfony

Question

I've got three classes. The File-Class has a reference to Foobar and Game inherits from Foobar. There are some other Classes which also inherit from Foobar but i left them out as they aren't relevant here. I also left out some unrelevant fields and their getters and setters.
The plan is that every Game has two images, the mainImage and the secondaryImage. I've put those fields into a seperate class from which Game inherits because i need them for a few other classes too.
My problem is that if I load the games from the database as soon as i try to iterate over them I get the following exception:
Notice: Undefined index: in C:\xampp\htdocs\Symfony\vendor\doctrine\mongodb-odm\lib\Doctrine\ODM\MongoDB\Mapping\ClassMetadataInfo.php line 1293
For reference here are the lines of ClassMetadataInfo.php
public function getPHPIdentifierValue($id)
{
$idType = $this->fieldMappings[$this->identifier]['type'];
return Type::getType($idType)->convertToPHPValue($id);
}
Here are my classes
File-Class:
namespace Project\MainBundle\Document;
use Doctrine\ODM\MongoDB\Mapping\Annotations as MongoDB;
/**
* #MongoDB\Document
*/
class File
{
/**
* #MongoDB\Id(strategy="INCREMENT")
*/
protected $id;
/**
* #MongoDB\ReferenceOne(targetDocument="Foobar", inversedBy="mainImage")
*/
private $mainImage;
/**
* #MongoDB\ReferenceOne(targetDocument="Foobar", inversedBy="secondaryImage")
*/
private $secondaryImage;
/**
* Get id
*/
public function getId()
{
return $this->id;
}
public function setMainImage($mainImage)
{
$this->mainImage = $mainImage;
return $this;
}
public function getMainImage()
{
return $this->mainImage;
}
public function setSecondaryImage($secondaryImage)
{
$this->secondaryImage = $secondaryImage;
return $this;
}
public function getSecondaryImage()
{
return $this->secondaryImage;
}
}
Foobar-Class:
namespace Project\MainBundle\Document;
use Doctrine\ODM\MongoDB\Mapping\Annotations as MongoDB;
/**
* #MongoDB\MappedSuperclass
*/
abstract class Foobar
{
/**
* #MongoDB\Id(strategy="INCREMENT")
*/
protected $id;
/**
* #MongoDB\ReferenceOne(targetDocument="File", mappedBy="mainImage")
*/
protected $mainImage;
/**
* #MongoDB\ReferenceOne(targetDocument="File", mappedBy="secondaryImage")
*/
protected $secondaryImage;
/**
* Get id
*/
public function getId()
{
return $this->id;
}
/**
* Set mainImage
*/
public function setMainImage($file)
{
$file->setMainImage($this);
$this->mainImage = $file;
return $this;
}
/**
* Get mainImage
*/
public function getMainImage()
{
return $this->mainImage;
}
/**
* Set secondaryImage
*/
public function setSecondaryImage($file)
{
$file->setSecondaryImage($this);
$this->secondaryImage = $file;
return $this;
}
/**
* Get secondaryImage
*/
public function getSecondaryImage()
{
return $this->secondaryImage;
}
}
Game-Class:
namespace Project\MainBundle\Document;
use Doctrine\ODM\MongoDB\Mapping\Annotations as MongoDB;
/**
* #MongoDB\Document
*/
class Game extends Foobar
{
/**
* #MongoDB\String
*/
private $name;
/**
* Set name
*/
public function setName($name)
{
$this->name = $name;
return $this;
}
/**
* Get name
*/
public function getName()
{
return $this->name;
}
}
Though it doesn't really matter but here is my function i want to execute:
$dm = $this->get('doctrine_mongodb')->getManager();
$games_all = $dm->getRepository("ProjectMainBundle:Game")->createQueryBuilder()->sort('id', 'ASC')->getQuery()->execute();
foreach ($games_all as $singlegame) { // it breaks here
// Here i would do stuff
}
Is this a bug in Doctrine ODM or am I doing something wrong? Are the classes correct? I have tried everything but it just wont work.

Answer 1

I think it is too late for your question, but maybe there are other users having the same problem (as me).
The problem is related to Foobar being a MappedSuperclass. Had the same problem as described by you and at https://github.com/doctrine/mongodb-odm/issues/241.
Solution is to not reference the abstract class Foobar (=MappedSuperclass) but a concrete implementation (=Document) - as in your case - Game.
See also Doctrine ODM returns proxy object for base class instead of sub-classed document