Ticket #35381: term_id.patch

src/wp-includes/class-wp-term-query.php

@@ -634 +634 @@
                 $cache = wp_cache_get( $cache_key, 'terms' );
                 if ( false !== $cache ) {
                         if ( 'all' === $_fields ) {
+                                _prime_term_caches( $cache, $args['update_term_meta_cache'] );
                                 $cache = array_map( 'get_term', $cache );
                         }
 
@@ -732 +733 @@
                         }
                 }
 
-                wp_cache_add( $cache_key, $terms, 'terms', DAY_IN_SECONDS );
-
                 if ( 'all' === $_fields ) {
-                        $terms = array_map( 'get_term', $terms );
+                        $terms    = array_map( 'get_term', $terms );
+                        $term_ids = wp_list_pluck( $terms, 'term_id' );
+                        wp_cache_add( $cache_key, $term_ids, 'terms', DAY_IN_SECONDS );
+                } else {
+                        wp_cache_add( $cache_key, $terms, 'terms', DAY_IN_SECONDS );
                 }
 
                 $this->terms = $terms;