fix: handle redirect thrown in handle hook in response to form action

.changeset/modern-years-tell.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: handle redirect thrown in handle hook in response to form action

packages/kit/src/runtime/server/page/actions.js

@@ -72,11 +72,7 @@ export async function handle_action_json_request(event, options, server) {
 		const err = normalize_error(e);
 
 		if (err instanceof Redirect) {
-			return action_json({
-				type: 'redirect',
-				status: err.status,
-				location: err.location
-			});
+			return action_json_redirect(err);
 		}
 
 		return action_json(
@@ -100,6 +96,17 @@ function check_incorrect_fail_use(error) {
 		: error;
 }
 
+/**
+ * @param {import('types').Redirect} redirect
+ */
+export function action_json_redirect(redirect) {
+	return action_json({
+		type: 'redirect',
+		status: redirect.status,
+		location: redirect.location
+	});
+}
+
 /**
  * @param {import('types').ActionResult} data
  * @param {ResponseInit} [init]

packages/kit/src/runtime/server/respond.js

@@ -26,6 +26,7 @@ import {
 } from '../../utils/exports.js';
 import { get_option } from '../../utils/options.js';
 import { error, json, text } from '../../exports/index.js';
+import { action_json_redirect, is_action_json_request } from './page/actions.js';
 
 /* global __SVELTEKIT_ADAPTER_NAME__ */
 
@@ -309,6 +310,8 @@ export async function respond(request, options, manifest, state) {
 		if (e instanceof Redirect) {
 			const response = is_data_request
 				? redirect_json_response(e)
+				: route?.page && is_action_json_request(event)
+				? action_json_redirect(e)
 				: redirect_response(e.status, e.location);
 			add_cookies_to_headers(response.headers, Object.values(cookies_to_add));
 			return response;

packages/kit/test/apps/basics/src/hooks.server.js

@@ -112,6 +112,13 @@ export const handle = sequence(
 			return event.fetch('/prerendering/prerendered-endpoint/api');
 		}
 
+		return resolve(event);
+	},
+	async ({ event, resolve }) => {
+		if (event.url.pathname === '/actions/redirect-in-handle' && event.request.method === 'POST') {
+			throw redirect(303, '/actions/enhance');
+		}
+
 		return resolve(event);
 	}
 );

packages/kit/test/apps/basics/src/routes/actions/redirect-in-handle/+page.server.js

@@ -0,0 +1,6 @@
+/** @type {import('./$types').Actions} */
+export const actions = {
+	default: async () => {
+		throw new Error('should never get here');
+	}
+};

packages/kit/test/apps/basics/src/routes/actions/redirect-in-handle/+page.svelte

@@ -0,0 +1,7 @@
+<script>
+	import { enhance } from '$app/forms';
+</script>
+
+<form method="post" use:enhance>
+	<button>Submit</button>
+</form>

packages/kit/test/apps/basics/test/test.js

@@ -1042,6 +1042,29 @@ test.describe('Actions', () => {
 		expect(page.url()).toContain('/actions/enhance');
 	});
 
+	test('redirect in handle', async ({ page, javaScriptEnabled }) => {
+		await page.goto('/actions/redirect-in-handle');
+
+		page.click('button');
+
+		const [redirect] = await Promise.all([
+			page.waitForResponse('/actions/redirect-in-handle'),
+			page.waitForNavigation()
+		]);
+		if (javaScriptEnabled) {
+			expect(await redirect.json()).toEqual({
+				type: 'redirect',
+				location: '/actions/enhance',
+				status: 303
+			});
+		} else {
+			expect(redirect.status()).toBe(303);
+			expect(redirect.headers()['location']).toBe('/actions/enhance');
+		}
+
+		expect(page.url()).toContain('/actions/enhance');
+	});
+
 	test('$page.status reflects error status', async ({ page, app }) => {
 		await page.goto('/actions/enhance');