Automatically update the sidebar trees for all users if the trees are changed somehow.

src/EntityListeners/TreeCacheInvalidationListener.php

@@ -75,6 +75,11 @@ class TreeCacheInvalidationListener
         if ($element instanceof AbstractStructuralDBElement || $element instanceof LabelProfile) {
             $secure_class_name = str_replace('\\', '_', get_class($element));
             $this->cache->invalidateTags([$secure_class_name]);
+
+            //Trigger a sidebar reload for all users (see SidebarTreeUpdater service)
+            if(!$element instanceof LabelProfile) {
+                $this->cache->invalidateTags(['sidebar_tree_update']);
+            }
         }
 
         //If a user change, then invalidate all cached trees for him

src/Services/Trees/SidebarTreeUpdater.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Services\Trees;
+
+use Symfony\Contracts\Cache\CacheInterface;
+use Symfony\Contracts\Cache\ItemInterface;
+use Symfony\Contracts\Cache\TagAwareCacheInterface;
+
+final class SidebarTreeUpdater
+{
+    private const CACHE_KEY = 'sidebar_tree_updated';
+    private const TTL = 60 * 60 * 24; // 24 hours
+
+    private CacheInterface $cache;
+
+    public function __construct(TagAwareCacheInterface $treeCache)
+    {
+        $this->cache = $treeCache;
+    }
+
+    /**
+     * Returns the time when the sidebar tree was updated the last time.
+     * The frontend uses this information to reload the sidebar tree.
+     * @return \DateTimeInterface
+     * @throws \Psr\SimpleCache\InvalidArgumentException
+     */
+    public function getLastTreeUpdate(): \DateTimeInterface
+    {
+        return $this->cache->get(self::CACHE_KEY, function (ItemInterface $item) {
+            $item->expiresAfter(self::TTL);
+
+            //This tag and therfore this whole cache gets cleared by TreeCacheInvalidationListener when a structural element is changed
+            $item->tag('sidebar_tree_update');
+
+            return new \DateTime();
+        });
+    }
+}