How to add a dynamic constraint on a form field - symfony

Question

I have a non required field in my 'Session' entity, field is named 'location'. I want to make it required only if another field is equal to true, this other property is named 'isVirtual'
I thaught i'd create an eventSubscriber with the event BeforeEntityUpdatedEvent but I don't know how to add a constraint and I am not sure when this event is triggered.
I tried to do a custom validation constraint but I don't know how to get value of 'isVirtual' value in my ConstraintValidator class.
I need someone to help me look in the right direction. I put there my Entity
<?php
namespace App\Entity;
use App\Repository\SessionRepository;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;
#[ORM\Entity(repositoryClass: SessionRepository::class)]
class Session
{
#[ORM\Id]
#[ORM\GeneratedValue]
#[ORM\Column]
private ?int $id = null;
#[ORM\Column]
private ?\DateTimeImmutable $beginsAt = null;
#[ORM\Column]
private ?\DateTimeImmutable $endsAt = null;
#[ORM\ManyToOne(inversedBy: 'sessions')]
#[ORM\JoinColumn(nullable: false)]
private ?Formation $formation = null;
#[ORM\ManyToOne(inversedBy: 'sessions')]
#[ORM\JoinColumn(nullable: true)]
private ?Location $location = null;
#[ORM\Column]
private ?bool $isVirtual = null;
#[ORM\OneToMany(mappedBy: 'session', targetEntity: UserSession::class)]
private Collection $users;
#[ORM\Column(nullable: true)]
private ?int $numberOfSeats = null;
public function __construct()
{
$this->users = new ArrayCollection();
}
public function getId(): ?int
{
return $this->id;
}
public function getBeginsAt(): ?\DateTimeImmutable
{
return $this->beginsAt;
}
public function setBeginsAt(\DateTimeImmutable $beginsAt): self
{
$this->beginsAt = $beginsAt;
return $this;
}
public function getEndsAt(): ?\DateTimeImmutable
{
return $this->endsAt;
}
public function setEndsAt(\DateTimeImmutable $endsAt): self
{
$this->endsAt = $endsAt;
return $this;
}
public function getFormation(): ?Formation
{
return $this->formation;
}
public function setFormation(?Formation $formation): self
{
$this->formation = $formation;
return $this;
}
public function getLocation(): ?Location
{
return $this->location;
}
public function setLocation(?Location $location): self
{
$this->location = $location;
return $this;
}
public function isIsVirtual(): ?bool
{
return $this->isVirtual;
}
public function setIsVirtual(bool $isVirtual): self
{
$this->isVirtual = $isVirtual;
return $this;
}
/**
* #return Collection<int, UserSession>
*/
public function getUsers(): Collection
{
return $this->users;
}
public function addUser(UserSession $user): self
{
if (!$this->users->contains($user)) {
$this->users->add($user);
$user->setSession($this);
}
return $this;
}
public function removeUser(UserSession $user): self
{
if ($this->users->removeElement($user)) {
// set the owning side to null (unless already changed)
if ($user->getSession() === $this) {
$user->setSession(null);
}
}
return $this;
}
public function getNumberOfSeats(): ?int
{
return $this->numberOfSeats;
}
public function setNumberOfSeats(int $numberOfSeats): self
{
$this->numberOfSeats = $numberOfSeats;
return $this;
}
public function retrieveSeat($number): self
{
$this->setNumberOfSeats($this->getNumberOfSeats() - $number);
return $this;
}
}
and my EasyAdmin Controller
<?php
namespace App\Controller\Admin;
use App\Entity\Session;
use EasyCorp\Bundle\EasyAdminBundle\Config\Crud;
use EasyCorp\Bundle\EasyAdminBundle\Field\IdField;
use EasyCorp\Bundle\EasyAdminBundle\Field\DateField;
use EasyCorp\Bundle\EasyAdminBundle\Field\BooleanField;
use EasyCorp\Bundle\EasyAdminBundle\Field\IntegerField;
use EasyCorp\Bundle\EasyAdminBundle\Field\AssociationField;
use EasyCorp\Bundle\EasyAdminBundle\Controller\AbstractCrudController;
class SessionCrudController extends AbstractCrudController
{
public static function getEntityFqcn(): string
{
return Session::class;
}
public function configureFields(string $pageName): iterable
{
return [
IdField::new('id')->hideOnForm(),
AssociationField::new('formation'),
DateField::new('beginsAt'),
DateField::new('endsAt'),
BooleanField::new('isVirtual'),
AssociationField::new('location')
->setRequired(false)
->setFormTypeOption('attr', ['placeholder' => 'Enter location']),
IntegerField::new('numberOfSeats')
->setRequired(false)
];
}
}
Thanks a lot in advance.

Answer 1

Here is the callback implementation. Thanks to craigh
<?php
namespace App\Entity;
........
use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\Validator\Context\ExecutionContextInterface;
class Session
{
........
#[Assert\Callback]
public function validate(ExecutionContextInterface $context, $payload)
{
if (!$this->isIsVirtual()) {
if ($this->getLocation() === null) {
$context->buildViolation("Session needs a location when it's not virtual")
->atPath('location')
->addViolation();
}
if ($this->getNumberOfSeats() === null) {
$context->buildViolation("Session needs a number of seats when it's not virtual")
->atPath('numberOfSeats')
->addViolation();
}
}
}
}