Doctrine relations for parent and child classes - php

Question

I'm trying to implement a doctrine relation for a symphony 3 app.
I have two different classes, one extending from the other, which are related to the same entity with a many to one relation.
Here are my classes.
Country.php
class Country
{
/**
* #var int
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
* #Groups({"exposed"})
*/
private $id;
/**
* #ORM\OneToMany(targetEntity="Link", mappedBy="country")
*/
private $link;
/**
* #ORM\OneToMany(targetEntity="LinkChild", mappedBy="country")
*/
private $linkChild;
public function __construct()
{
$this->link = new ArrayCollection();
$this->linkChild = new ArrayCollection();
}
}
Link.php
/**
* Link
*
* #ORM\Table(name="link")
* #ORM\Entity(repositoryClass="Decathlon\AppCollaboratorBundle\Reposito\LinkRepository")
* #Vich\Uploadable
* #ORM\HasLifecycleCallbacks()
*/
class Link
{
/**
* #var int
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
* #Serializer\Groups({"link_list", "link_info"})
* #Serializer\Expose()
*/
protected $id;
/**
* #var Country
*
* #ORM\ManyToOne(targetEntity="Country", inversedBy="link", cascade={"persist"})
* #JoinColumn(name="country_id", referencedColumnName="id")
*/
protected $country;
}
LinkChild.php
/**
* #ORM\Entity(repositoryClass="Decathlon\AppCollaboratorBundle\Repository\LinkChildRepository")
*/
class LinkChild extends Link
{
/**
* #var Country
*
* #ORM\ManyToOne(targetEntity="Country", inversedBy="linkChild", cascade={"persist"})
* #JoinColumn(name="country_id", referencedColumnName="id")
*/
protected $country;
}
I need to create a relation between both Link and LinkChild to Country but no country column is created in LinkChild table.
I've told not to use recursive classes so I must create Link and LinkChild.
Is there a way to acomplish what I'm tryng to do.
Thank you in advance.

Answer 1

I think what you are looking for is single table inheritance?
<?php
namespace MyProject\Model;
/**
* #Entity
* #InheritanceType("SINGLE_TABLE")
* #DiscriminatorColumn(name="discr", type="string")
* #DiscriminatorMap({"person" = "Person", "employee" = "Employee"})
*/
class Person
{
// ...
}
/**
* #Entity
*/
class Employee extends Person
{
// ...
}
Take a look here:
http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/inheritance-mapping.html#single-table-inheritance

Answer 2

Try renaming your protected $country; variable to something like private $childCountry; to make it a variable that belongs specifically to LinkChild.
Your protected $country; override in LinkChild is ignored because it is exactly the same as the one in Link.