Symfony 3 Doctrine 2: Circular reference on relations - php

Question

I'm trying to get working 4 entities in Symfony 3 with Doctrine 2 but I'm stuck on a circular reference exception when I want to serialize an Account entity for example:
A circular reference has been detected (configured limit: 1).
I chose bi-directional relations in my entities and schema is like this:
- Account [1] ---- [0..*] AccountSheet
- AccountSheet [1] ---- [0..*] Operation
- Operation [0..*] ---- [1] Category
Here are entities (with some cleanings for clarity):
src\AppBundle\Entity\Account.php
<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;
use AppBundle\Entity\AbstractGenericEntity;
/**
* #ORM\Entity()
* #ORM\Table(name="accounts",
* uniqueConstraints={#ORM\UniqueConstraint(name="accounts_name_unique",columns={"name"})})
*/
class Account extends AbstractGenericEntity{
/**
* #ORM\OneToMany(targetEntity="AccountSheet", mappedBy="account")
* #var AccountSheet[]
*/
protected $accountSheets;
public function __construct($name = null, $description = null){
$this->accountSheets = new ArrayCollection();
$this->name = $name;
$this->description = $description;
}
}
src\AppBundle\Entity\AccountSheet.php
<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;
use AppBundle\Entity\AbstractGenericEntity;
/**
* #ORM\Entity()
* #ORM\Table(name="accounts_sheets",
* uniqueConstraints={#ORM\UniqueConstraint(name="accountsheet_account_unique", columns={"name", "account_id"})})
* #ORM\HasLifecycleCallbacks
*/
class AccountSheet extends AbstractGenericEntity{
/**
* #ORM\ManyToOne(targetEntity="AppBundle\Entity\Account", inversedBy="accountSheets")
* #var Account
*/
protected $account;
/**
* #ORM\OneToMany(targetEntity="Operation", mappedBy="accountSheet")
* #var Operation[]
*/
protected $operations;
public function __construct($name = null){
$this->operations = new ArrayCollection();
$this->name = $name;
}
}
src\AppBundle\Entity\Operation.php
<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use AppBundle\Entity\AbstractGenericEntity;
/**
* #ORM\Entity()
* #ORM\Table(name="operations")
*/
class Operation extends AbstractGenericEntity{
/**
* #ORM\ManyToOne(targetEntity="AppBundle\Entity\AccountSheet", inversedBy="operations")
* #ORM\JoinColumn(nullable=false)
* #var AccountSheet
*/
protected $accountSheet;
/**
* #ORM\ManyToOne(targetEntity="AppBundle\Entity\Category", inversedBy="operations")
* #var Category
*/
protected $category;
public function __construct($type = null, $label = null, $montant = null, $comment = null){
$this->label = $label;
$this->type = $type;
$this->comment = $comment;
$this->montant = $montant;
}
}
src\AppBundle\Entity\Category.php
<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;
use AppBundle\Entity\AbstractGenericEntity;
/**
* #ORM\Entity()
* #ORM\Table(name="categories")
*/
class Category extends AbstractGenericEntity{
/**
* #ORM\Column(type="string")
*/
protected $label;
/**
* #ORM\Column(type="string")
*/
protected $description;
/**
* #ORM\OneToMany(targetEntity="Operation", mappedBy="category")
* #var Operation[]
*/
protected $operations;
public function __construct($name = null){
$this->operations = new ArrayCollection();
$this->name = $name;
}
}
I guess it's on the Operation entity, where AccountSheet is referenced again. The bi-directional on operation is not really needed.
How could I rearrange this?
Thanks!

Answer 1

From the official documentation :
Circular references are common when dealing with entity relations
To avoid infinite loops, GetSetMethodNormalizer throws a CircularReferenceException when such a case is encountered:
$member = new Member();
$member->setName('Kévin');
$org = new Organization();
$org->setName('Les-Tilleuls.coop');
$org->setMembers(array($member));
$member->setOrganization($org);
echo $serializer->serialize($org, 'json'); // Throws a CircularReferenceException
So, from this point, you have 3 solutions to get rid of this issue :
Set a circular reference handler :
Instead of throwing an exception, circular references can also be handled by custom callables. This is especially useful when serializing entities having unique identifiers:
$encoder = new JsonEncoder();
$normalizer = new ObjectNormalizer();
$normalizer->setCircularReferenceHandler(function ($object) {
return $object->getName();
});
$serializer = new Serializer(array($normalizer), array($encoder));
var_dump($serializer->serialize($org, 'json'));
// {"name":"Les-Tilleuls.coop","members":[{"name":"K\u00e9vin", organization: "Les-Tilleuls.coop"}]}
Set ignored attributes (not my preferred solution) :
in your case :
$encoder = new JsonEncoder();
$normalizer = new ObjectNormalizer();
normalizer->setIgnoredAttributes(array("account", "accountSheet", "category", "operation"));
$serializer = new Serializer(array($normalizer), array($encoder));
var_dump($serializer->serialize($org, 'json'));
Use group attributes (my preferred solution) :
This method is similar to setting ignored attributes because you will chose which attribute you want to serialize by adding the group annotation on it and the rest will be ignored for recursivity during normalization process.
Using Serialization Groups Annotations
Attributes Groups
In your case with the Account entity for example do this on the account side :
<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;
use AppBundle\Entity\AbstractGenericEntity;
use Symfony\Component\Serializer\Annotation\Groups;
/**
* #ORM\Entity()
* #ORM\Table(name="accounts",
* uniqueConstraints={#ORM\UniqueConstraint(name="accounts_name_unique",columns={"name"})})
*/
class Account extends AbstractGenericEntity{
/**
* #ORM\OneToMany(targetEntity="AccountSheet", mappedBy="account")
* #var AccountSheet[]
* #Groups({"account"})
*/
protected $accountSheets;
public function __construct($name = null, $description = null){
$this->accountSheets = new ArrayCollection();
$this->name = $name;
$this->description = $description;
}
}
Then do not put this group annotation on the $account field in the AccountSheet entity to get rid of the circular reference issue.
Finally you serialize your Account :
$encoder = new JsonEncoder();
$normalizer = new ObjectNormalizer();
$serializer = new Serializer(array($normalizer), array($encoder));
var_dump($serializer->serialize($account, 'json', array('groups' => array('account')) ));

Answer 2

$jsonContent = $serializer->serialize($yourObject, 'json', [
'circular_reference_handler' => function ($object) {
return $object->getId();
}
]);
Above code works for me to fix circular reference exception. (Symfony >=4.2)