The question relates to the technology stack I use:
- Symfony 4.2.3
- Doctrine ORM 2.6.3
- Sonata Admin 3.45.2
- sqlite3 3.22 (although the RDBMS shouldn't play a role)
Let's say we have two entities: Category and Product where the relation category to product is 1:n and product to category is n:1. This would look like:
Category.php
class Category
{
// ...
/**
* @ORM\OneToMany(
* targetEntity="App\Entity\Product",
* mappedBy="category",
* cascade={"persist"}
* )
* @Assert\Valid()
*/
private $products;
// ...
}
Product.php
class Product
{
// ...
/**
* @ORM\ManyToOne(
* targetEntity="App\Entity\Category",
* inversedBy="samplingDocumentations"
* )
* @ORM\JoinColumn(nullable=false)
* @Assert\NotBlank()
*/
private $samplingActivity;
// ...
}
Product must be assigned to a Category. Category can have 0 or more Products. If Category contains any Products it must NOT be deleted. Category can be deleted only if no Products are assigned to it.
When I try to delete a Category which has Products in the Sonata Admin, the deletion is prevented, as expected, and an Exception is thrown:
PDOException
SQLSTATE[23000]: Integrity constraint violation: 19 FOREIGN KEY constraint failed
Now, that is expected, but not very nice for the end user. I'd like to provide a message and inform the user that the Category can not be deleted because it still holds Products.
In Sonata Admin I use a workaround, writing CategoryAdminController and implementing the preDelete hook:
public function preDelete(Request $request, $object)
{
if ($object->getProducts()->isEmpty()) {
return null;
}
$count = $object->getProducts()->count();
$objectName = $this->admin->toString($object);
$this->addFlash(
'sonata_flash_error',
sprintf(
'The category "%s" can not be deleted because it contains %s product(s).',
$objectName,
$count
)
);
return $this->redirectTo($object);
}
However this doesn't feel right, because I have to reimplement it outside the admin.
What is the best practice to handle this? Can I implement some kind of validation in the entity? Or maybe Doctrine event listeners are the right thing?
I believe what you are trying to do is described here:
Symfony + Doctrine - Define an error message when integrity constraint error
I won't copy-paste the whole message, but the concept is to create onKernelResponse listener and listen for PDOException. How to do this there are lot of articles, I believe you can easily find online, I've selected one of the first that I've found.
Within that Listener you can determine what exception it is and use flashbag either a default symfony one:
https://symfony.com/doc/current/components/http_foundation/sessions.html
$session->getFlashBag()->add('notice', 'Profile updated');
Or you could use Sonata Core Flashbag:
https://sonata-project.org/bundles/core/master/doc/reference/flash_messages.html
To use this feature in your PHP classes/controllers:
$flashManager = $this->get('sonata.core.flashmessage.manager');
$messages = $flashManager->get('success');
To use this feature in your templates, include the following template (with an optional domain parameter):
{% include '@SonataCore/FlashMessage/render.html.twig' %}
Note If necessary, you can also specify a translation domain to override configuration here:
{% include '@SonataCore/FlashMessage/render.html.twig' with { domain: 'MyCustomBundle' } %}
You can also take a look at this article https://tocacar.com/symfony2-how-to-modify-sonataadminbundles-error-message-on-entity-deletion-ca77cac343fa and override CRUDController::deleteAction so you can handle such errors.
And here you can find some code, that is related to your issue a bit, on Sonata Admin GitHub page https://github.com/sonata-project/SonataAdminBundle/issues/4485
it catches PDOException, so also check what version you are using, maybe what you need is an update.
I managed to solve the problem by adding a custom listener. It catches the ModelManagerException when deleting a restricted object. It works for all registered admins. Here is the class:
<?php
namespace App\EventListener;
use Symfony\Component\HttpFoundation\Session\SessionInterface;
use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
use Doctrine\ORM\EntityManagerInterface;
use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
use Symfony\Component\HttpFoundation\RedirectResponse;
use Sonata\AdminBundle\Exception\ModelManagerException;
class ModelManagerExceptionResponseListener
{
private $session;
private $router;
private $em;
public function __construct(SessionInterface $session, UrlGeneratorInterface $router, EntityManagerInterface $em)
{
$this->session = $session;
$this->router = $router;
$this->em = $em;
}
public function onKernelException(GetResponseForExceptionEvent $event)
{
// get the exception
$exception = $event->getException();
// we proceed only if it is ModelManagerException
if (!$exception instanceof ModelManagerException) {
return;
}
// get the route and id
// if it wasn't a delete route we don't want to proceed
$request = $event->getRequest();
$route = $request->get('_route');
$id = $request->get('id');
if (substr($route, -6) !== 'delete') {
return;
}
$route = str_replace('delete', 'edit', $route);
// get the message
// we proceed only if it is the desired message
$message = $exception->getMessage();
$failure = 'Failed to delete object: ';
if (strpos($message, $failure) < 0) {
return;
}
// get the object that can't be deleted
$entity = str_replace($failure, '', $message);
$repository = $this->em->getRepository($entity);
$object = $repository->findOneById($id);
$this->session->getFlashBag()
->add(
'sonata_flash_error',
sprintf('The item "%s" can not be deleted because other items depend on it.', $object)
)
;
// redirect to the edit form of the object
$url = $this->router->generate($route, ['id' => $id]);
$response = new RedirectResponse($url);
$event->setResponse($response);
}
}
And we register the service:
app.event_listener.pdoexception_listener:
class: App\EventListener\ModelManagerExceptionResponseListener
arguments:
- '@session'
- '@router'
- '@doctrine.orm.entity_manager'
tags:
- { name: kernel.event_listener, event: kernel.exception }
public: true # this maybe isn't needed
Probably deleting of any object outside the admin will not be allowed in my particular case. Therefore this solution satisfies the requirements. I hope that this example can help others. You'll have to adapt some parts according to your needs.
