Are Value objects associations possible? - doctrine-orm

Question

I wonder whether it's possible to have relations between entities and value objects or if a third entity is mandatory as relation target. The purpose could be to flag different kind of entities with a common data structure that has it's own business logic. Any idea ?
Update :
Let's say I have a business object to model SCAP CPE namings :
<?php
namespace Scap\Cpe\Naming;
/**
* Cpe22 represents the naming convention in CPE Naming version 2.2
* Accepted values are only CPE URIs
*/
class Cpe22
{
protected $cpe;
public function __construct($cpe)
{
if (! preg_match('/[c][pP][eE]:\/[AHOaho]?(:[A-Za-z0-9\._\-~%]*){0,6}/', $cpe)) {
throw new InvalidNamingException();
}
$this->cpe = $cpe;
}
}
If I want to flag different kind of entities with this VO in a one-to-many way, I can think of 2 different ways :
Entities are directly related to VOs so that the relation identifiers could be the entities references and the VOs themselves (= key composed from referenced identifier and representative VO fields)
Entities are related to third entity types, that embed the VOs so that the relation identifiers are those third entities identifiers
So I wonder if only the second option is available or if the first can somehow be implemented.

Answer 1

You should use a custom mapping type for things like this. For example, it could look something like this:
use Doctrine\DBAL\Types\Type;
use Doctrine\DBAL\Platforms\AbstractPlatform
class Cpe22Type extends Type
{
public function getSQLDeclaration(array $fieldDeclaration, AbstractPlatform $platform)
{
return $platform->getVarcharTypeDeclarationSQL(array('length' => 250));
}
public function convertToPHPVale($value, AbstractPlatform $platform)
{
return new Cpe22($value);
}
public function convertToDatabaseValue($value, AbstractPlatform $platform)
{
return (string) $value;
}
public function getName()
{
return 'cpe22';
}
public function requiresSQLCommentHint(AbstractPlatform $platform)
{
return true;
}
}
Obviously, you have to add a __toString() method to your Cpe22 class for this to work.
After registering the type (how you do this depends on your framework, in symfony for example you do it in config.yml) you can simply map your field as type cpe22:
/**
* #ORM\Column(name="my_cpe", type="cpe22")
*/
public $myCpe;