Symfony2-Doctrine2 inheritance persist not working properly - php

Question

I have a project in Symfony 2.3, using Doctrine ORM 2.3.4, and I'm using class inheritance:
a parent class
/**
* #ORM\Entity
* #ORM\Table(name="parent")
* #ORM\InheritanceType("JOINED")
* #ORM\DiscriminatorColumn(name="discr", type="string")
* #ORM\DiscriminatorMap({"child"="Child"})
*/
class Parent
{
/**
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
public function getId()
{
return $this->id;
}
// other fields & methods
}
and a child one
/**
* #ORM\Entity
* #ORM\Table(name="child")
*/
class Child extends Parent
{
/**
* #ORM\Column(name="id", type="integer")
* #ORM\Id
*/
private $id;
public function getId()
{
return $this->id;
}
}
The problem comes when I persist the child object, flush and then I try to retrieve the child id:
// ChildController::createAction
$em = $this->getDoctrine()->getManager();
$child = new Child();
// set child fields
$em->persist($child);
$em->flush();
$child->getId(); // <- not working
On the database the child row is saved correctly, and if I change the child method getId
public function getId()
{
return parent::getId();
}
it works.
Can anyone please explain this to me?
Many thanks.

Answer 1

The parent entity needs to give visibility of it's properties to it's children.
Change your $id property visibility to "protected".

Answer 2

It's a little bit late, but maybe it helps others.
When you take a look at your table definition that Doctrine generated, you will see why it is this way. E.g. mine in postgres:
...
CONSTRAINT fk_5d9f75a1bf396750 FOREIGN KEY (id)
REFERENCES parent (id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE CASCADE
...
As you can see, Doctrine uses for your child table id the id of the parent.
Like #John Cartwright said, make your $id in parent protected.
In addition to this define the getter only in the parent and everything works just fine.