Add BeforeFormValidateEvent for new and edit actions

Add a new event dispatched after form submission but before validation.
This allows developers to:
- Perform complex cross-field validation
- Return a custom Response (e.g., for AJAX integrations)
- Modify entity or form data before validation runs

The event is dispatched in both new() and edit() actions.

Fix #7509

Author: Amoifr

src/Controller/AbstractCrudController.php

@@ -33,6 +33,7 @@
 use EasyCorp\Bundle\EasyAdminBundle\Event\BeforeEntityDeletedEvent;
 use EasyCorp\Bundle\EasyAdminBundle\Event\BeforeEntityPersistedEvent;
 use EasyCorp\Bundle\EasyAdminBundle\Event\BeforeEntityUpdatedEvent;
+use EasyCorp\Bundle\EasyAdminBundle\Event\BeforeFormValidateEvent;
 use EasyCorp\Bundle\EasyAdminBundle\Exception\EntityRemoveException;
 use EasyCorp\Bundle\EasyAdminBundle\Exception\ForbiddenActionException;
 use EasyCorp\Bundle\EasyAdminBundle\Exception\InsufficientEntityPermissionException;
@@ -263,6 +264,15 @@ public function edit(AdminContext $context): KeyValueStore|Response
 
         $editForm = $this->createEditForm($context->getEntity(), $context->getCrud()->getEditFormOptions(), $context);
         $editForm->handleRequest($context->getRequest());
+
+        if ($editForm->isSubmitted()) {
+            $event = new BeforeFormValidateEvent($entityInstance, $editForm);
+            $this->container->get('event_dispatcher')->dispatch($event);
+            if ($event->isPropagationStopped()) {
+                return $event->getResponse();
+            }
+        }
+
         if ($editForm->isSubmitted() && $editForm->isValid()) {
             $this->processUploadedFiles($editForm);
 
@@ -327,6 +337,14 @@ public function new(AdminContext $context): KeyValueStore|Response
         $entityInstance = $newForm->getData();
         $context->getEntity()->setInstance($entityInstance);
 
+        if ($newForm->isSubmitted()) {
+            $event = new BeforeFormValidateEvent($entityInstance, $newForm);
+            $this->container->get('event_dispatcher')->dispatch($event);
+            if ($event->isPropagationStopped()) {
+                return $event->getResponse();
+            }
+        }
+
         if ($newForm->isSubmitted() && $newForm->isValid()) {
             $this->processUploadedFiles($newForm);
 

src/Event/BeforeFormValidateEvent.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace EasyCorp\Bundle\EasyAdminBundle\Event;
+
+use Symfony\Component\Form\FormInterface;
+
+/**
+ * Event dispatched after form submission but before validation.
+ * This allows to perform custom validation, modify data, or return
+ * a custom response before the standard validation runs.
+ *
+ * @author Javier Eguiluz <javier.eguiluz@gmail.com>
+ *
+ * @template TEntity of object
+ *
+ * @extends AbstractLifecycleEvent<TEntity>
+ */
+final class BeforeFormValidateEvent extends AbstractLifecycleEvent
+{
+    use StoppableEventTrait;
+
+    /**
+     * @param TEntity $entityInstance
+     */
+    public function __construct(
+        protected object $entityInstance,
+        private readonly FormInterface $form,
+    ) {
+    }
+
+    public function getForm(): FormInterface
+    {
+        return $this->form;
+    }
+}