[6.x] Serialize nocache regions before storing in cache

src/StaticCaching/NoCache/DatabaseSession.php

@@ -30,7 +30,7 @@ public function region(string $key): Region
             throw new RegionNotFound($key);
         }
 
-        return unserialize($region->region);
+        return unserialize($region->region, ['allowed_classes' => true]);
     }
 
     protected function cacheRegion(Region $region)

src/StaticCaching/NoCache/Session.php

@@ -51,7 +51,13 @@ public function regions(): Collection
     public function region(string $key): Region
     {
         if ($this->regions->contains($key) && ($region = StaticCache::cacheStore()->get('nocache::region.'.$key))) {
-            return $region;
+            if ($region instanceof Region) {
+                return $region;
+            }
+
+            if (is_string($region)) {
+                return unserialize($region, ['allowed_classes' => true]);
+            }
         }
 
         throw new RegionNotFound($key);
@@ -150,6 +156,6 @@ protected function resolvePageAndPathForPagination(): void
 
     protected function cacheRegion(Region $region)
     {
-        StaticCache::cacheStore()->forever('nocache::region.'.$region->key(), $region);
+        StaticCache::cacheStore()->forever('nocache::region.'.$region->key(), serialize($region));
     }
 }

tests/StaticCaching/NoCacheSessionTest.php

@@ -6,7 +6,9 @@
 use Illuminate\Support\Facades\Cache;
 use Mockery;
 use PHPUnit\Framework\Attributes\Test;
+use Statamic\Facades\StaticCache;
 use Statamic\StaticCaching\Cacher;
+use Statamic\StaticCaching\NoCache\RegionNotFound;
 use Statamic\StaticCaching\NoCache\Session;
 use Statamic\StaticCaching\NoCache\StringRegion;
 use Tests\FakesContent;
@@ -148,6 +150,39 @@ public function it_restores_from_cache()
         $this->assertEquals('http://localhost/cp', $cascade['cp_url']);
     }
 
+    #[Test]
+    public function it_serializes_and_unserializes_regions_through_cache()
+    {
+        $session = new Session('http://localhost/test');
+
+        $region = $session->pushRegion('the contents', ['foo' => 'bar'], '.html');
+
+        $cached = StaticCache::cacheStore()->get('nocache::region.'.$region->key());
+        $this->assertIsString($cached, 'Region should be stored as a serialized string, not an object.');
+
+        $retrieved = $session->region($region->key());
+
+        $this->assertInstanceOf(StringRegion::class, $retrieved);
+        $this->assertEquals($region->key(), $retrieved->key());
+        $this->assertEquals(['foo' => 'bar'], $retrieved->context());
+    }
+
+    #[Test]
+    public function it_throws_region_not_found_when_cached_region_is_an_incomplete_class()
+    {
+        $session = new Session('http://localhost/test');
+
+        $region = $session->pushRegion('the contents', ['foo' => 'bar'], '.html');
+
+        // Simulate what happens when serializable_classes enforcement
+        // turns a cached Region object into __PHP_Incomplete_Class.
+        StaticCache::cacheStore()->forever('nocache::region.'.$region->key(), new \__PHP_Incomplete_Class);
+
+        $this->expectException(RegionNotFound::class);
+
+        $session->region($region->key());
+    }
+
     #[Test]
     public function a_singleton_is_bound_in_the_container()
     {