FEATURE: Make formState initialization extendable

Classes/Core/Runtime/FormRuntime.php

@@ -26,6 +26,7 @@
 use Neos\Form\Core\Renderer\RendererInterface;
 use Neos\Form\Exception\PropertyMappingException;
 use Neos\Form\Exception\RenderingException;
+use Neos\Form\FormState\FormStateInitializerChain;
 use Neos\Utility\Arrays;
 
 /**
@@ -99,6 +100,12 @@ class FormRuntime implements RootRenderableInterface, \ArrayAccess
      */
     protected $formState;
 
+    /**
+     * @Flow\Inject
+     * @var FormStateInitializerChain
+     */
+    protected $formStateInitializerChain;
+
     /**
      * The current page is the page which will be displayed to the user
      * during rendering.
@@ -162,30 +169,14 @@ public function __construct(FormDefinition $formDefinition, ActionRequest $reque
      */
     public function initializeObject()
     {
-        $this->initializeFormStateFromRequest();
+        $this->formState = $this->formStateInitializerChain->initializeFormState($this->formDefinition, $this->request);
         $this->initializeCurrentPageFromRequest();
 
         if (!$this->isFirstRequest()) {
             $this->processSubmittedFormValues();
         }
     }
 
-    /**
-     * @return void
-     * @internal
-     */
-    protected function initializeFormStateFromRequest()
-    {
-        $serializedFormStateWithHmac = $this->request->getInternalArgument('__state');
-        if ($serializedFormStateWithHmac === null) {
-            $this->formState = new FormState();
-        } else {
-            $serializedFormState = $this->hashService->validateAndStripHmac($serializedFormStateWithHmac);
-            /** @noinspection UnserializeExploitsInspection The unserialize call is safe because of the HMAC check above */
-            $this->formState = unserialize(base64_decode($serializedFormState));
-        }
-    }
-
     /**
      * @return void
      * @internal

Classes/FormState/FormStateInitializerChain.php

@@ -0,0 +1,47 @@
+<?php
+declare(strict_types=1);
+
+namespace Neos\Form\FormState;
+
+/*
+ * This file is part of the Neos.Form package.
+ *
+ * (c) Contributors of the Neos Project - www.neos.io
+ *
+ * This package is Open Source Software. For the full copyright and license
+ * information, please view the LICENSE file which was distributed with this
+ * source code.
+ */
+
+use Neos\Flow\Annotations as Flow;
+use Neos\Flow\Mvc\ActionRequest;
+use Neos\Form\Core\Model\FormDefinition;
+use Neos\Form\Core\Runtime\FormState;
+use Neos\Utility\PositionalArraySorter;
+
+final class FormStateInitializerChain
+{
+
+    /**
+     * @Flow\InjectConfiguration(path="formStateInitializerChain")
+     * @var string[][]
+     */
+    protected $formStateInitializerChain;
+
+    public function initializeFormState(FormDefinition $formDefinition, ActionRequest $actionRequest): FormState
+    {
+        $formState = new FormState();
+        $sortedChain = (new PositionalArraySorter($this->formStateInitializerChain))->toArray();
+
+        foreach ($sortedChain as $initializer) {
+            $class = $initializer['class'] ?? '';
+            if (!is_a($class, FormStateInitializerInterface::class, true)) {
+                throw new \RuntimeException(sprintf('The given class "%s" does not implement the interface %s', $class, FormStateInitializerInterface::class), 1648204540);
+            }
+
+            $formState = (new $class())->initializeState($formDefinition, $actionRequest, $formState);
+        }
+
+        return $formState;
+    }
+}

Classes/FormState/FormStateInitializerInterface.php

@@ -0,0 +1,23 @@
+<?php
+declare(strict_types=1);
+
+namespace Neos\Form\FormState;
+
+/*
+ * This file is part of the Neos.Form package.
+ *
+ * (c) Contributors of the Neos Project - www.neos.io
+ *
+ * This package is Open Source Software. For the full copyright and license
+ * information, please view the LICENSE file which was distributed with this
+ * source code.
+ */
+
+use Neos\Flow\Mvc\ActionRequest;
+use Neos\Form\Core\Model\FormDefinition;
+use Neos\Form\Core\Runtime\FormState;
+
+interface FormStateInitializerInterface
+{
+    public function initializeState(FormDefinition $formDefinition, ActionRequest $actionRequest, FormState $previousFormState): FormState;
+}

Classes/FormState/SerializedFormStateArgumentInitializer.php

@@ -0,0 +1,43 @@
+<?php
+declare(strict_types=1);
+
+namespace Neos\Form\FormState;
+
+/*
+ * This file is part of the Neos.Form package.
+ *
+ * (c) Contributors of the Neos Project - www.neos.io
+ *
+ * This package is Open Source Software. For the full copyright and license
+ * information, please view the LICENSE file which was distributed with this
+ * source code.
+ */
+
+use Neos\Flow\Annotations as Flow;
+use Neos\Flow\Mvc\ActionRequest;
+use Neos\Flow\Security\Cryptography\HashService;
+use Neos\Form\Core\Model\FormDefinition;
+use Neos\Form\Core\Runtime\FormState;
+
+class SerializedFormStateArgumentInitializer implements FormStateInitializerInterface
+{
+
+    /**
+     * @Flow\Inject
+     * @var HashService
+     * @internal
+     */
+    protected $hashService;
+
+    public function initializeState(FormDefinition $formDefinition, ActionRequest $actionRequest, FormState $previousFormState): FormState
+    {
+        $serializedFormStateWithHmac = $actionRequest->getInternalArgument('__state');
+        if ($serializedFormStateWithHmac !== null) {
+            $serializedFormState = $this->hashService->validateAndStripHmac($serializedFormStateWithHmac);
+            /** @noinspection UnserializeExploitsInspection The unserialize call is safe because of the HMAC check above */
+            return unserialize(base64_decode($serializedFormState));
+        }
+
+        return $previousFormState;
+    }
+}

Configuration/Settings.yaml

@@ -3,8 +3,10 @@ Neos:
   Form:
     yamlPersistenceManager:
       savePath: '%FLOW_PATH_DATA%Forms/'
+
     supertypeResolver:
       hiddenProperties: {  }
+
     presets:
       default:
         title: Default
@@ -200,3 +202,8 @@ Neos:
             implementationClassName: Neos\Flow\Validation\Validator\RegularExpressionValidator
           'Neos.Flow:Count':
             implementationClassName: Neos\Flow\Validation\Validator\CountValidator
+
+    formStateInitializerChain:
+      serializedFormStateArgument:
+        class: 'Neos\Form\FormState\SerializedFormStateArgumentInitializer'
+        position: 'start'