[BUGFIX] Invalidate backend preview caches on each DataHandler operation

Fixes: #171

Classes/Backend/Preview/PageLayout.php

@@ -156,7 +156,7 @@ protected function getContentBlockData(
             if ($resolvedData->resolved !== $pageRow) {
                 try {
                     $exported = 'return ' . VarExporter::export($resolvedData) . ';';
-                    $this->cache->set($cacheIdentifier, $exported);
+                    $this->cache->set($cacheIdentifier, $exported, ['content_blocks_preview'], 0);
                 } catch (NotInstantiableTypeException) {
                     // @todo objects of class TYPO3\CMS\Core\Resource\File can't be exported
                     // @todo due to attached storage, which itself has EventDispatcher attached

Classes/Backend/Preview/PreviewRenderer.php

@@ -83,7 +83,7 @@ public function renderPageModulePreviewContent(GridColumnItem $item): string
             if ($resolvedData->resolved !== $record) {
                 try {
                     $exported = 'return ' . VarExporter::export($resolvedData) . ';';
-                    $this->cache->set($cacheIdentifier, $exported);
+                    $this->cache->set($cacheIdentifier, $exported, ['content_blocks_preview'], 0);
                 } catch (NotInstantiableTypeException) {
                     // @todo objects of class TYPO3\CMS\Core\Resource\File can't be exported
                     // @todo due to attached storage, which itself has EventDispatcher attached

Classes/DataHandler/ClearBackendPreviewCaches.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+namespace TYPO3\CMS\ContentBlocks\DataHandler;
+
+use TYPO3\CMS\Core\Cache\CacheManager;
+use TYPO3\CMS\Core\DataHandling\DataHandler;
+
+/**
+ * @internal Not part of TYPO3's public API.
+ */
+class ClearBackendPreviewCaches
+{
+    public function __construct(
+        protected readonly CacheManager $cacheManager,
+    ) {}
+
+    public function processDatamap_afterAllOperations(DataHandler $dataHandler): void
+    {
+        // This is just a simple solution for invalidating preview caches after
+        // each DataHandler operation. It is not easy to make selective picks
+        // as relations can get as complex as needed.
+        $this->cacheManager->flushCachesByTag('content_blocks_preview');
+    }
+}

Configuration/Services.yaml

@@ -14,6 +14,9 @@ services:
   TYPO3\CMS\ContentBlocks\Cache\InitializeContentBlockCache:
     public: true
 
+  TYPO3\CMS\ContentBlocks\DataHandler\ClearBackendPreviewCaches:
+    public: true
+
 # @todo change to BeforeTcaOverridesEvent for v13
   TYPO3\CMS\ContentBlocks\Generator\TcaGenerator:
     public: true

ext_localconf.php

@@ -2,6 +2,8 @@
 
 defined('TYPO3') or die();
 
+use TYPO3\CMS\ContentBlocks\DataHandler\ClearBackendPreviewCaches;
+use TYPO3\CMS\Core\Cache\Backend\FileBackend;
 use TYPO3\CMS\Core\Cache\Backend\SimpleFileBackend;
 use TYPO3\CMS\Core\Cache\Frontend\PhpFrontend;
 use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;
@@ -44,11 +46,13 @@
 
 $GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['content_blocks_preview'] = [
     'frontend' => PhpFrontend::class,
-    'backend' => SimpleFileBackend::class,
+    'backend' => FileBackend::class,
     'options' => [
         'defaultLifetime' => 0,
     ],
     'groups' => ['system'],
 ];
 
+$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_tcemain.php']['processDatamapClass'][] = ClearBackendPreviewCaches::class;
+
 $GLOBALS['TYPO3_CONF_VARS']['SYS']['fluid']['namespaces']['cb'][] = 'TYPO3\\CMS\\ContentBlocks\\ViewHelpers';