Use serialize instead of implode because transient keys must depend o…

…n request keys.

src/wp-includes/rest-api/endpoints/class-wp-rest-pattern-directory-controller.php

@@ -367,14 +367,12 @@ protected function get_transient_key( $query_args ) {
 			// Sort the array so that the transient key doesn't depend on the order of slugs.
 			sort( $query_args['slug'] );
 
-			// Slugs have to be imploded separately as implode doesn't work with recursive arrays.
-			$query_args['slug'] = implode( ',', $query_args['slug'] );
-
-			if ( '' === trim( $query_args['slug'] ) ) {
+			// Empty arrays should not affect the transient key.
+			if ( 0 === count( $query_args['slug'] ) ) {
 				unset( $query_args['slug'] );
 			}
 		}
 
-		return 'wp_remote_block_patterns_' . md5( implode( '-', $query_args ) );
+		return 'wp_remote_block_patterns_' . md5( serialize( $query_args ) );
 	}
 }

tests/phpunit/tests/rest-api/rest-pattern-directory-controller.php

@@ -473,6 +473,16 @@ public function data_get_query_parameters() {
 				),
 				'message' => 'The order of slugs should not affect transient key.',
 			),
+			array(
+				array(
+					'parameter_1' => 1,
+					'slug'        => array(),
+				),
+				array(
+					'parameter_1' => 1,
+				),
+				'message' => 'Transient keys must match.',
+			),
 			array(
 				array(
 					'parameter_1' => 1,
@@ -485,6 +495,16 @@ public function data_get_query_parameters() {
 				'message' => 'Transient keys must not match.',
 				false,
 			),
+			array(
+				array(
+					'parameter_1' => 1,
+				),
+				array(
+					'parameter_2' => 1,
+				),
+				'message' => 'Transient keys must depend on array keys.',
+				false,
+			),
 		);
 	}