prePersist to check null object - symfony

Question

I have this class:
* #ORM\Entity
* #ORM\HasLifecycleCallbacks()
class Parameter{
/**
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
* #ORM\ManyToOne(targetEntity="Project\Bundle\Entity\Anthropometry", inversedBy="parameter")
* #ORM\JoinColumn(name="anthropometry_id", referencedColumnName="id")
*
*/
protected $anthropometry;
/**
* #ORM\Column(name="data", type="string", length=255, nullable=true)
*/
protected $data;
...
}
and this:
/**
* #ORM\Table(name="anthropometry")
* #ORM\Entity
*/
class Anthropometry {
/**
* #var integer $id
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
*
* #ORM\OneToMany(targetEntity="Project\Bundle\Entity\Parameter", mappedBy="anthropometry", cascade={"persist"})
*
*/
protected $parameter;
...
}
In my Controller I am creating a form and validating in the same Action.
To create the form I need instance one Parameter. But not need persist him.
So.. when I call $em->flush I got the error:
A new entity was found through the relationship ...
To solve this I put cascade={"persist"} in annotation:
//Class Anthropometry
...
/**
*
* #ORM\OneToMany(targetEntity="Project\Bundle\Entity\Parameter", mappedBy="anthropometry", cascade={"persist"})
*
*/
protected $parameter;
But now, in my Database, the parameters are being persisted with field 'Data' = NULL
Can I check with prePersist if the field is NULL before persist?
something like this?
//class Parameter
/**
*
* #ORM\prePersist
*/
public function prePersist(){
if($this->getData() == NULL){
return false;
}
}
Thx!

Answer 1

I didn't verify if it works but you could try unsetting the parameter before persisting the Anthropometry (since you don't need to persist parameters):
//class Anthropometry
/**
* #ORM\prePersist
*/
public function prePersist()
{
if(!is_null($this->parameter) && $this->parameter->getData() == null){
$this->parameter = null;
}
}