Using data of Doctrine Collection from OneToMany association in JSON - php

Question

I've seen many examples of how to set up a OneToMany association between Entities. However, I have not seen anything on how to output the data from an association. (such as converting to JSON or just having a clean array)
So, here is some sample code:
declare(strict_types=1);
namespace Banks\Entity;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
/**
* https://www.doctrine-project.org/projects/doctrine-orm/en/2.6/reference/basic-mapping.html
*
* #ORM\Entity
* #ORM\Table(name="bank")
**/
class Banks implements \JsonSerializable
{
/**
* #ORM\Id
* #ORM\Column(type="integer", name="id", nullable=false)
* #ORM\GeneratedValue(strategy="IDENTITY")
*/
protected $id;
/**
* A Bank could have Many Branches
*
* #ORM\OneToMany(targetEntity="Branches\Entity\Branches", mappedBy="bank")
*
*/
protected $branches;
/**
* #ORM\Column(type="string", nullable=true)
*/
protected $name;
/**
*
* #return array|mixed
*/
public function jsonSerialize()
{
return [
'id' => $this->id,
'name' => $this->name,
'branches' => $this->getBranches()
];
}
public function __construct()
{
$this->branches = new ArrayCollection();
}
public function getBranches(): Collection
{
return $this->branches;
}
// ... Other getter/setters removed
}
Then we also have the Branches Entity:
declare(strict_types=1);
namespace Branches\Entity;
use Doctrine\ORM\Mapping as ORM;
/**
* https://www.doctrine-project.org/projects/doctrine-orm/en/2.6/reference/basic-mapping.html
*
* #ORM\Entity
* #ORM\Table(name="branches")
**/
class Branches implements \JsonSerializable
{
/**
* #ORM\Id
* #ORM\Column(type="integer", nullable=false)
* #ORM\GeneratedValue(strategy="IDENTITY")
*/
protected $id;
/**
* A Branch has one Bank
*
* #ORM\ManyToOne(targetEntity="Banks\Entity\Banks", inversedBy="branches")
* #ORM\JoinColumn(name="bank_id", referencedColumnName="id")
*/
protected $bank;
/**
* #ORM\Column(type="integer", nullable=false)
*/
protected $bank_id;
/**
* #ORM\Column(type="string", nullable=true)
*/
protected $name;
/**
*
* #return array|mixed
*/
public function jsonSerialize()
{
return [
'id' => $this->id,
'bank_id' => $this->bank_id,
'name' => $this->name,
'bank' => $this->getBank()
];
}
public function getBank()
{
return $this->bank;
}
// ... Other getter/setters removed
}
Querying both Entities work fine overall, with calls to $result->jsonSerialize(), then returning with return new JsonResponse($result) to get a JSON object. Though querying a Branch has the expected result, where I receive the Branch along with the associated Bank as part of the output, the query to Bank is not returning the associated Branches and instead only displays as "branches": {}
I know this is because $branches is a Collection, but how to output it in a way to be part of the resulting JSON object?
I've tried $this->branches->toArray(), but that results in an array of Objects that cannot be encoded to JSON, therefore, ending in an error.
NOTE: The contents (Object) of $this->getBranches() does contain the Branches as expected, which can be seen by $this->branches->count(). But how to reach them in such a way to allow JsonSerializable to create the JSON?
As requested, here is middleware code leaving up to Entity usage:
A factory is used to create what is needed by the Handler:
class BanksViewHandlerFactory
{
public function __invoke(ContainerInterface $container) : BanksViewHandler
{
$entityManager = $container->get(EntityManager::class);
$entityManager->getConfiguration()->addEntityNamespace('Banks', 'Banks\Entity');
$entityRepository = $entityManager->getRepository('Banks:Banks');
return new BanksViewHandler($entityManager, $entityRepository);
}
}
The Factory calls the Handler:
class BanksViewHandler implements RequestHandlerInterface
{
protected $entityManager;
protected $entityRepository;
public function __construct(
EntityManager $entityManager,
EntityRepository $entityRepository,
) {
$this->entityManager = $entityManager;
$this->entityRepository = $entityRepository;
}
public function handle(ServerRequestInterface $request) : ResponseInterface
{
$return = $this->entityRepository->find($request->getAttribute('id'));
$result['Result']['Banks'] = $return->jsonSerialize();
return new JsonResponse($result);
}
}
The handler returns the JSON.

Answer 1

It's important to note that, when implementing the \JsonSerializable interface, calling jsonSerialize() directly does not return JSON, and you do not call this method explicitly.
As stated in the docs:
Objects implementing JsonSerializable can customize their JSON representation when encoded with json_encode().
The intent of implementing this interface is to enforce the jsonSerialize() method, which is called internally when passing the object(s) to json_encode(); e.g:
$result = $banksRepository->find($id);
$json = json_encode($result);
Additionally, if you want to serialize the child Branch entities as well you need to:
Implement \JsonSerializable for this entity (which you have done)
Doctrine will return these Branches as an ArrayCollection object, containing all child Branch objects. In order to ensure that json_encode() encodes these to JSON properly you need to convert the ArrayCollection to an array using toArray().
To illustrate - (as you pointed out you also implemented this):
public function jsonSerialize()
{
return [
'id' => $this->id,
'name' => $this->name,
'branches' => $this->getBranches()->toArray(), // <--
];
}
This should serialise your Bank and associated Branch entities as expected. Hope this helps :)