REST API: Return empty object when no fallback templates are found (w…

…p/v2/templates/lookup)

This prevents a number of php notices that are surfaced due to the endpoint being called on load of the post editor even when there are no templates.

Props grantmkin, CookiesForDevo, britner, wildworks, jorbin.
Fixes #60909.


git-svn-id: https://develop.svn.wordpress.org/trunk@58079 602fd350-edb4-49c9-b593-d223f7449a82

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

@@ -165,7 +165,8 @@ public function get_template_fallback( $request ) {
 			array_shift( $hierarchy );
 		} while ( ! empty( $hierarchy ) && empty( $fallback_template->content ) );
 
-		$response = $this->prepare_item_for_response( $fallback_template, $request );
+		// To maintain original behavior, return an empty object rather than a 404 error when no template is found.
+		$response = $fallback_template ? $this->prepare_item_for_response( $fallback_template, $request ) : new stdClass();
 
 		return rest_ensure_response( $response );
 	}

tests/phpunit/tests/rest-api/wpRestTemplatesController.php

@@ -909,6 +909,19 @@ public function test_get_template_fallback() {
 		$this->assertSame( 'index', $response->get_data()['slug'], 'Should fallback to `index.html` when  ignore_empty is `true`.' );
 	}
 
+	/**
+	 * @ticket 60909
+	 * @covers WP_REST_Templates_Controller::get_template_fallback
+	 */
+	public function test_get_template_fallback_not_found() {
+		wp_set_current_user( self::$admin_id );
+		$request = new WP_REST_Request( 'GET', '/wp/v2/templates/lookup' );
+		$request->set_param( 'slug', 'not-found' );
+		$response = rest_get_server()->dispatch( $request );
+		$data     = $response->get_data();
+		$this->assertEquals( new stdClass(), $data, 'Response should be an empty object when a fallback template is not found.' );
+	}
+
 	/**
 	 * @ticket 57851
 	 *