[4.x] Update child URIs when parent slug changes

src/Entries/UpdateStructuredEntryChildUris.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace Statamic\Entries;
+
+use Statamic\Events\EntrySaved;
+
+class UpdateStructuredEntryChildUris
+{
+    public function handle(EntrySaved $event)
+    {
+        $entry = $event->entry;
+        $collection = $entry->collection();
+
+        // If it's orderable (single depth structure) then changing the
+        // position of the entries is never going to affect the uris.
+        if ($collection->orderable()) {
+            return;
+        }
+
+        // If the collection has no route, there are no uris to update.
+        if (! $collection->route($entry->locale())) {
+            return;
+        }
+
+        // If there's no page, there are no children to update.
+        if (! $page = $entry->page()) {
+            return;
+        }
+
+        $ids = $page->flattenedPages()->pluck('id');
+
+        if (empty($ids)) {
+            return;
+        }
+
+        $collection->updateEntryUris($ids);
+    }
+}

src/Providers/EventServiceProvider.php

@@ -20,6 +20,9 @@ class EventServiceProvider extends ServiceProvider
             \Statamic\Entries\UpdateStructuredEntryUris::class,
             \Statamic\Entries\UpdateStructuredEntryOrder::class,
         ],
+        \Statamic\Events\EntrySaved::class => [
+            \Statamic\Entries\UpdateStructuredEntryChildUris::class,
+        ],
         \Statamic\Events\EntryBlueprintFound::class => [
             \Statamic\Entries\AddSiteColumnToBlueprint::class,
         ],