fix: clear cached featured image when its attachment changes

src/Base/RestAPI/ItemFields/FeaturedImageField.php

@@ -7,6 +7,13 @@
 
 class FeaturedImageField extends CreatesFields
 {
+    private const CACHE_KEY = 'openpub_featured_image_%d';
+
+    /**
+     * Attachment meta that ends up in the cached field.
+     */
+    private const CACHED_META_KEYS = ['_wp_attachment_metadata', '_wp_attached_file', '_wp_attachment_image_alt'];
+
     /**
      * Gets the featured image of a post.
      *
@@ -21,7 +28,7 @@ public function create(WP_Post $post): array
         }
 
         $id = \get_post_thumbnail_id($post->ID);
-        $cacheKey = sprintf('openpub_featured_image_%d', $id);
+        $cacheKey = sprintf(self::CACHE_KEY, $id);
         $cached = get_transient($cacheKey);
 
         if (is_array($cached)) {
@@ -50,6 +57,21 @@ public function create(WP_Post $post): array
         return $result;
     }
 
+    public function clearCache(int $attachmentId): void
+    {
+        delete_transient(sprintf(self::CACHE_KEY, $attachmentId));
+    }
+
+    /**
+     * Image editor saves (crop, rotate, scale, restore) only touch attachment meta.
+     */
+    public function clearCacheOnMetaChange(int $metaId, int $objectId, string $metaKey): void
+    {
+        if (in_array($metaKey, self::CACHED_META_KEYS, true)) {
+            $this->clearCache($objectId);
+        }
+    }
+
     /**
      * Get meta data of an attachment.
      */

src/Base/RestAPI/RestAPIServiceProvider.php

@@ -7,6 +7,7 @@
 use OWC\OpenPub\Base\RestAPI\Controllers\SearchController;
 use OWC\OpenPub\Base\RestAPI\Controllers\SettingsController;
 use OWC\OpenPub\Base\RestAPI\Controllers\ThemeController;
+use OWC\OpenPub\Base\RestAPI\ItemFields\FeaturedImageField;
 use WP_REST_Server;
 
 class RestAPIServiceProvider extends ServiceProvider
@@ -22,6 +23,13 @@ public function register(): void
         $this->plugin->loader->addFilter('rest_api_init', $this, 'registerRoutes');
         $this->plugin->loader->addFilter('owc/config-expander/rest-api/whitelist', $this, 'whitelist', 10, 1);
 
+        // Before cache purges on the default priority, so a portal refetch never rebuilds from the stale image.
+        $featuredImageField = new FeaturedImageField($this->plugin);
+        $this->plugin->loader->addAction('updated_post_meta', $featuredImageField, 'clearCacheOnMetaChange', 5, 3);
+        $this->plugin->loader->addAction('added_post_meta', $featuredImageField, 'clearCacheOnMetaChange', 5, 3);
+        $this->plugin->loader->addAction('edit_attachment', $featuredImageField, 'clearCache', 5, 1);
+        $this->plugin->loader->addAction('delete_attachment', $featuredImageField, 'clearCache', 5, 1);
+
         $this->registerModelFields();
     }
 

tests/Unit/Base/RestAPI/ItemFields/FeaturedImageFieldTest.php

@@ -224,4 +224,45 @@ public function it_returns_a_correct_featured_image_response_with_multiple_size(
         ];
         $this->assertEquals($expected, $actual);
     }
+
+    /** @test */
+    public function it_clears_the_cached_image_of_an_attachment()
+    {
+        WP_Mock::userFunction('delete_transient', [
+            'args'  => ['openpub_featured_image_2'],
+            'times' => 1,
+        ]);
+
+        (new FeaturedImageField($this->plugin))->clearCache(2);
+
+        $this->assertTrue(true);
+    }
+
+    /** @test */
+    public function it_clears_the_cached_image_when_the_attachment_is_edited()
+    {
+        WP_Mock::userFunction('delete_transient', [
+            'args'  => ['openpub_featured_image_2'],
+            'times' => 3,
+        ]);
+
+        $featuredImageField = new FeaturedImageField($this->plugin);
+        $featuredImageField->clearCacheOnMetaChange(10, 2, '_wp_attachment_metadata');
+        $featuredImageField->clearCacheOnMetaChange(10, 2, '_wp_attached_file');
+        $featuredImageField->clearCacheOnMetaChange(10, 2, '_wp_attachment_image_alt');
+
+        $this->assertTrue(true);
+    }
+
+    /** @test */
+    public function it_keeps_the_cached_image_on_unrelated_meta_changes()
+    {
+        WP_Mock::userFunction('delete_transient', [
+            'times' => 0,
+        ]);
+
+        (new FeaturedImageField($this->plugin))->clearCacheOnMetaChange(10, 2, '_edit_lock');
+
+        $this->assertTrue(true);
+    }
 }

tests/Unit/Base/RestAPI/RestAPIServiceProviderTest.php

@@ -6,6 +6,7 @@
 use OWC\OpenPub\Base\Foundation\Config;
 use OWC\OpenPub\Base\Foundation\Loader;
 use OWC\OpenPub\Base\Foundation\Plugin;
+use OWC\OpenPub\Base\RestAPI\ItemFields\FeaturedImageField;
 use OWC\OpenPub\Base\RestAPI\RestAPIServiceProvider;
 use OWC\OpenPub\Tests\TestCase;
 use WP_Mock;
@@ -69,6 +70,26 @@ public function check_registration_of_rest_endpoints()
             'registerRoutes'
         ])->once();
 
+        foreach (['updated_post_meta', 'added_post_meta'] as $hook) {
+            $plugin->loader->shouldReceive('addAction')->withArgs([
+                $hook,
+                m::type(FeaturedImageField::class),
+                'clearCacheOnMetaChange',
+                5,
+                3
+            ])->once();
+        }
+
+        foreach (['edit_attachment', 'delete_attachment'] as $hook) {
+            $plugin->loader->shouldReceive('addAction')->withArgs([
+                $hook,
+                m::type(FeaturedImageField::class),
+                'clearCache',
+                5,
+                1
+            ])->once();
+        }
+
         $configRestAPIFields = [
             'posttype1' => [
                 'endpoint_field1' =>