[FEATURE] Make it possible to assign variables to view (#1199)

In event FormControllerFormActionEvent, make it possible to assign
variables to view.

Related: #1198

Author: sypets

Classes/Controller/FormController.php

@@ -80,6 +80,9 @@ public function formAction(): ResponseInterface
         $event = $this->eventDispatcher->dispatch(
             GeneralUtility::makeInstance(FormControllerFormActionEvent::class, $form, $this)
         );
+        if ($event->getViewVariables()) {
+            $this->view->assignMultiple($event->getViewVariables());
+        }
         $form = $event->getForm();
         SessionUtility::saveFormStartInSession($this->settings, $form);
         $this->view->assignMultiple(

Classes/Events/FormControllerFormActionEvent.php

@@ -18,6 +18,11 @@ final class FormControllerFormActionEvent
      */
     protected FormController $formController;
 
+    /**
+     * @var array<string,mixed>
+     */
+    protected array $viewVariables = [];
+
     /**
      * @param Form|null $form
      * @param FormController $formController
@@ -53,4 +58,23 @@ public function getFormController(): FormController
     {
         return $this->formController;
     }
+
+    /**
+     * @return array<string,mixed>
+     */
+    public function getViewVariables(): array
+    {
+        return $this->viewVariables;
+    }
+
+    /**
+     * Add additional variables to the view
+     *
+     * @param array<string,mixed> $variables
+     * @return void
+     */
+    public function addViewVariables(array $variables): void
+    {
+        $this->viewVariables = array_merge($this->viewVariables, $variables);
+    }
 }