SPA onUpdate() doesn't show errors set by setError() on subsequent submits

[huyquanha]

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Description

In SPA mode, the first time the form is submitted and onUpdate() is invoked, any additional errors added by setError() are successfully displayed.

When a field is further modified, the errors are gone (which is expected).

However, when the form is submitted a 2nd/3rd time..., and the form still contains errors such that setError() is called again in onUpdate(), the errors are no longer displayed.

Below is an example src/routes/login/+page.svelte that suffers from this. I can see the API call still being made, so onUpdate() is definitely still invoked on subsequent submits. Hence, the issue is more likely with setError()

<script lang="ts">
	import * as Form from '$lib/components/ui/form';
	import * as Card from '$lib/components/ui/card/index.js';
	import { Input } from '$lib/components/ui/input/index.js';
	import { superForm, defaults, setError } from 'sveltekit-superforms';
	import { zod } from 'sveltekit-superforms/adapters';
	import { loginFormSchema, type LoginFormSchema } from './schema';
	import SuperDebug from 'sveltekit-superforms';
	import { getProfileClient } from '$lib/connect/profile-client.svelte';
	import { Code, ConnectError } from '@connectrpc/connect';
	import { BadRequestSchema } from '$lib/protogen/google/rpc/error_details_pb';
	import { goto } from '$app/navigation';
	import { toast } from 'svelte-sonner';
	import * as Alert from '$lib/components/ui/alert';
	import CircleAlert from 'lucide-svelte/icons/circle-alert';

	const profileClient = getProfileClient();

	const form = superForm(defaults(zod(loginFormSchema)), {
		SPA: true,
		validators: zod(loginFormSchema),
		onUpdate: async ({ form, result }) => {
			if (form.valid) {
				const { email, password } = form.data;
				try {
					await profileClient.login({
						email,
						password
					});
					toast.success('You have successfully logged in!');
					// navigate the user to the home page with a flash message.
					return goto('/');
				} catch (err) {
					result.type = 'failure';
					const connectErr = ConnectError.from(err);
					const errCode = connectErr.code;
					// TODO: log errCode and errMsg in Sentry.
					// const errMsg = connectErr.rawMessage;
					switch (errCode) {
						case Code.InvalidArgument: {
							connectErr.findDetails(BadRequestSchema).find((i) => {
								const violations = i.fieldViolations;
								for (const violation of violations) {
									const field = violation.field;
									const message = violation.description;
									let formField: '' | LoginFormSchema = '';
									switch (field) {
										case 'email':
										case 'password':
											formField = field;
											break;
										default:
											break;
									}
									setError(form, formField, message);
								}
								result.status = 400;
							});
							break;
						}
						case Code.NotFound:
							result.status = 404;
							setError(form, 'No account found with that email address');
							break;
						case Code.Unauthenticated:
							result.status = 401; // Unauthorized
							setError(form, 'Email or password is incorrect');
							break;
						default:
							result.status = 500;
							setError(form, 'An unexpected error occurred when creating your account');
					}
				}
			}
		}
	});

	const { form: formData, errors, allErrors, enhance } = form;

	let hasFormLevelErrors = $derived($errors._errors && $errors._errors.length > 0);

	let hasFormErrors = $derived($allErrors.length > 0);
</script>

<SuperDebug data={$formData} />

<div class="flex min-h-screen flex-col">
	{#if hasFormLevelErrors}
		<Alert.Root variant="destructive" class="mx-auto mb-1 mt-auto max-w-sm">
			<CircleAlert class="size-4" />
			<Alert.Title>Error</Alert.Title>
			<Alert.Description>
				<ul>
					{#each $errors._errors || [] as error}
						<li>{error}</li>
					{/each}
				</ul>
			</Alert.Description>
		</Alert.Root>
	{/if}
	<Card.Root class="mx-auto {hasFormLevelErrors ? 'mb-auto mt-1' : 'my-auto'} max-w-sm">
		<Card.Header>
			<Card.Title class="text-xl">Login</Card.Title>
			<Card.Description>Enter your email below to login to your account</Card.Description>
		</Card.Header>
		<Card.Content>
			<div class="grid gap-4">
				<form method="POST" use:enhance>
					<Form.Field {form} name="email">
						<Form.Control>
							{#snippet children({ props })}
								<Form.Label>Email</Form.Label>
								<Input {...props} type="email" bind:value={$formData.email} />
							{/snippet}
						</Form.Control>
						<Form.FieldErrors />
					</Form.Field>
					<Form.Field {form} name="password">
						<Form.Control>
							{#snippet children({ props })}
								<Form.Label>Password</Form.Label>
								<Input {...props} type="password" bind:value={$formData.password} />
							{/snippet}
						</Form.Control>
						<Form.FieldErrors />
					</Form.Field>
					<Form.Button class="mt-4 w-full" disabled={hasFormErrors}>Log in</Form.Button>
				</form>
				<Form.Button variant="outline" class="w-full">Log in with Google</Form.Button>
			</div>
			<div class="mt-4 text-center text-sm">
				Do not have an account?
				<a href="/signup" class="underline"> Sign up </a>
			</div>
		</Card.Content>
	</Card.Root>
</div>

If applicable, a MRE
Use this template project to create a minimal reproducible example that you can link to here: https://sveltelab.dev/github.com/ciscoheat/superforms-examples/tree/zod (right click to open in a new tab)

[huyquanha]

Side note, it seems like result.type = 'failure' is necessary for the errors to be displayed, but it's not mentioned in the documentation.

Also, setError status option (to change the status code) doesn't seem to take any effect. I have to set result.status = ... explicitly (as seen in the example above). However, none of these are blockers, just thought you should know

[ciscoheat]

Are you on the latest SvelteKit? This has just been fixed: #536

[huyquanha]

@ciscoheat thanks! updating to 2.15.2 indeed fixed it. And it looks like I no longer need to set result.type = 'failure' anymore which's great.

However, setError() status option still doesn't seem like it's working as expected. It should be 404 here instead of 200. To make it 404, I still have to write result.status = 404 explicitly.

I don't think this has big impact to SPA though, just a bit confusing if someone is debugging things with <SuperDebug/>

[ciscoheat]

Yes, form and result are kind of disconnected in the onUpdate event, so result takes precedence. I'll add a note that you cannot use status in setMessage for SPA.