Foreign key stays empty after persisting entity with OneToMany association - doctrine-orm

Question

Given are the following two entity classes
<?php
namespace App\Entity;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Entity()
* #ORM\Table()
*/
class Tree
{
/**
* #ORM\Id()
* #ORM\Column(type="guid")
* #ORM\GeneratedValue(strategy="UUID")
* #var string
*/
private $id;
/**
* #ORM\OneToMany(targetEntity="Apple", mappedBy="tree", cascade={"persist"})
* #var Collection
*/
private $apples;
public function __construct()
{
$this->setApples(new ArrayCollection());
}
public function toArray(): array
{
return [
'id' => $this->getId(),
];
}
public function getId(): string
{
return $this->id;
}
public function setId(string $id): void
{
$this->id = $id;
}
public function getApples(): Collection
{
return $this->apples;
}
public function setApples(Collection $apples): void
{
$this->apples = $apples;
}
}
<?php
namespace App\Entity;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Entity()
* #ORM\Table()
*/
class Apple
{
/**
* #ORM\Id()
* #ORM\Column(type="guid")
* #ORM\GeneratedValue(strategy="UUID")
* #var string
*/
private $id;
/**
* #ORM\ManyToOne(targetEntity="Tree", inversedBy="apples")
* #var Tree
*/
private $tree;
public function toArray(): array
{
return [
'id' => $this->getId(),
];
}
public function getId(): string
{
return $this->id;
}
public function setId(string $id): void
{
$this->id = $id;
}
public function getTree(): Tree
{
return $this->tree;
}
public function setTree(Tree $tree): void
{
$this->tree = $tree;
}
}
The database schema looks good except for apple.tree_id being nullable. Is that already an issue in this case?
I'm persisting entries like the following:
<?php
declare(strict_types = 1);
namespace App\Service;
use App\Entity\Apple;
use App\Entity\Tree;
use Doctrine\ORM\EntityManager;
class Gardener
{
private $entityManager;
public function __construct(EntityManager $entityManager)
{
$this->entityManager = $entityManager;
}
public function plantTree(): array
{
$entityManager = $this->entityManager;
$tree = new Tree();
$blueApple = new Apple();
$redApple = new Apple();
$tree->getApples()->add($blueApple);
$tree->getApples()->add($redApple);
$entityManager->persist($tree);
$entityManager->flush();
return (array) $tree;
}
}
When executing the persist and flush there are no errors or warnings. A tree an two apple entries are beingt store, the apple.tree_id is however always null.
It seems like I have a misconfiguration on the entity classes, but am not sure what it is. I also tried adding a JoinColumn annotation #ORM\JoinColumn(name="tree_id", referencedColumnName="id"), but it did not make any difference.
What changes do I need to make, to have appe.tree_id being set properly?

Answer 1

Your missing the adder & remover functions on the *ToMany side.
If your using Symfony >4 then replace setApples function with:
public function addApple(Apple $apple): Tree
{
$this->apples->add($apple);
return $this;
}
public function removeApple(Apple $apple): Tree
{
$this->apples->removeElement($apple);
return $this;
}
If you're using Zend Framework 3, then replace setApples function with:
public function addApples(array $apples): Tree
{
foreach ($apples as $apple) {
if (! $this->apples->contains($apple) {
$this->apples->add($apple)
$apple->setTree($this);
}
}
return $this;
}
public function removeApples(array $apples): Tree
{
foreach ($apples as $apple) {
if($this->apples->contains($apple) {
$this->apples->remove($apple);
}
}
return $this;
}
Have a read of the Working with Association docs, which show examples and explain how to update back 'n' forth.