Symfony 5 Object Serialization with ManyToMany Relation Times Out - symfony

Question

In my Symfony 5 application, I have an entity class Product which has two properties $categories and $bundles. The product class has a ManyToMany relation with both the properties. When I comment out either one of the properties the Product serialization works perfectly. But incase both properties are present the serialization times out.
The code excerpt from Product class.
class Product
{
/**
* #ORM\ManyToMany(targetEntity=ProductBundle::class, mappedBy="products")
*/
private $productBundles;
/**
* #ORM\ManyToMany(targetEntity=Category::class, mappedBy="products")
* #MaxDepth(1)
*/
private $categories;
}
The code for the serialization is below.
$products = $productRepository->findBySearchQuery($name);
$productsJson = $serializerInterface->serialize($products, 'json', [
ObjectNormalizer::CIRCULAR_REFERENCE_HANDLER => function ($object) {
return $object->getId();
}
]);
I have tried using the #ORM/JoinTable annotation suggested on some other Stackoverflow answers and #MaxDepth as well but no luck. The code works if any of the properties are commented out. Would be grateful for any advice on this.

Answer 1

okay, 20 products is actually not much. so I guess you're outputting the same objects over and over again if you let the relations be serialized unhindered.
I actually don't know how to achieve this reliably with the serializer. But the standard ways would just be enough probably. I like serializing via the JsonSerializable interface on your entities like this (omitting the ORM stuff for brevity):
class Product implements \JsonSerializable {
public $name;
public $categories; // relation
// getters + setters omitted
// this implements \JsonSerializable
public function jsonSerialize() {
return [
'name' => $this->name,
'categories' => array_map(function($category) {
return $category->jsonSerializeChild();
}, $this->categories),
];
}
// this function effectively stops recursion by leaving out relations
public function jsonSerializeChild() {
return [
'name' => $this->name,
];
}
}
If you implement this on all your entities you can very effectively limit the depth of serialization to two (i.e. the "base" entities and their connected entities).
also, the symfony serializer will use the JsonSerializable interface if it's defined if your serializing to JSON. Obviously, this is not as elegant as some fancy annotation-based serialization or a "smart" serializer, that actually manages to stop ... but it'll probably work better...

Answer 2

Pointed out by #Jakumi the serializer was looping over and over the object properties $categories and $bundles. I avoided that by using the Serialization groups.
The product class
class Product
{
/**
* #ORM\ManyToMany(targetEntity=ProductBundle::class, mappedBy="products")
* #Groups("product_listing:read")
*/
private $productBundles;
/**
* #ORM\ManyToMany(targetEntity=Category::class, mappedBy="products")
* #Groups("product_listing:read")
*/
private $categories;
}
The category class
class Category
{
/**
* #ORM\Id
* #ORM\GeneratedValue
* #ORM\Column(type="integer")
* #Groups("product_listing:read")
*/
private $id;
/**
* #ORM\Column(type="string", length=255)
* #Groups("product_listing:read")
*/
private $name;
}
The call to serializer
$products = $productRepository->findBySearchQuery($name);
$productsJson = $serializerInterface->serialize($products, 'json', ['groups' => 'product_listing:read']);
I hope this helps someone in future.