Fix woocommerce object cache

src/modules/woo-commerce/front.php

@@ -3,11 +3,28 @@
     exit;
 }
 
+/**
+ * Translate product terms after WooCommerce retrieves them from cache.
+ *
+ * WooCommerce product-term cache keys do not include the current language,
+ * so a persistent object cache may return terms translated during an
+ * earlier request in another language.
+ *
+ * @param array $terms Product terms.
+ *
+ * @return array
+ */
+function qtranxf_wc_translate_product_terms( $terms ) {
+    return qtranxf_useTermLib( $terms );
+}
+
 function qtranxf_wc_add_filters_front(): void {
 
     remove_filter( 'get_post_metadata', 'qtranxf_filter_postmeta', 5 );
     add_filter( 'get_post_metadata', 'qtranxf_wc_filter_postmeta', 5, 4 );
 
+    add_filter( 'woocommerce_get_product_terms', 'qtranxf_wc_translate_product_terms', 20, 1 );
+
     $front_hooks = array(
         'woocommerce_attribute'                       => 20,
         'woocommerce_attribute_label'                 => 20,

src/modules/woo-commerce/loader.php

@@ -7,6 +7,16 @@
 }
 
 function qtranxf_wc_init_language( array $url_info ): void {
+    /*
+     * WooCommerce caches the filtered result of
+     * `woocommerce_attribute_taxonomies`. Since qTranslate-XT translates
+     * this result, a persistent object cache would store the language of
+     * the first request for all subsequent requests.
+     */
+    if ( function_exists( 'wp_cache_add_non_persistent_groups' ) ) {
+        wp_cache_add_non_persistent_groups( array( 'woocommerce-attributes' ) );
+    }
+
     if ( $url_info['doing_front_end'] ) {
         require_once __DIR__ . '/front.php';
     } else {

src/taxonomy.php

@@ -33,24 +33,28 @@ function qtranxf_term_set_i18n_config( $term ) {
  */
 function qtranxf_term_use( string $lang, $obj, $taxonomy ) {
     global $q_config;
+
     if ( is_array( $obj ) ) {
-        // handle arrays recursively
+        // Handle arrays recursively.
         foreach ( $obj as $key => $term ) {
             $obj[ $key ] = qtranxf_term_use( $lang, $term, $taxonomy );
         }
 
         return $obj;
     }
+
     if ( is_object( $obj ) ) {
-        // object conversion
         if ( ! isset( $obj->i18n_config ) ) {
             qtranxf_term_set_i18n_config( $obj );
-            if ( isset( $obj->i18n_config['name']['ts'][ $lang ] ) ) {
-                $obj->name = $obj->i18n_config['name']['ts'][ $lang ];
-            }
-            if ( isset( $obj->i18n_config['description']['ts'][ $lang ] ) ) {
-                $obj->description = $obj->i18n_config['description']['ts'][ $lang ];
-            }
+        }
+
+        if ( isset( $obj->i18n_config['name']['ts'][ $lang ] ) ) {
+            $obj->name = $obj->i18n_config['name']['ts'][ $lang ];
+        }
+
+        if ( isset( $obj->i18n_config['description']['ts'][ $lang ] ) ) {
+            $obj->description =
+                $obj->i18n_config['description']['ts'][ $lang ];
         }
     } elseif ( isset( $q_config['term_name'][ $obj ][ $lang ] ) ) {
         $obj = $q_config['term_name'][ $obj ][ $lang ];