Remote functions Forms optional fields are always included in request

[jere2101]

Describe the bug

In my repo i have input field that is optional and when it's filled it has to be an json object with a specific structure ( in my case an array with coordinates ).
I've the following validation in my schema:

{
...
bounds: v.optional(v.pipe(v.string(), transformJson, boundsSchema))
...
}

transformJson = v.transform((input: string) => {
	try {
		return JSON.parse(input);
	} catch {
		return {};
	}
});

const boundsSchema = v.array(v.tuple([v.number(), v.number()]));

My Problem is that an empty Input Text field is included as an empty string in the request to the remote function.

I don't know if this is the default behavior from now on and i have to bypass this with some conditional validation or if this is just a bug with the transformation from the form data to an object.

Thanks for your help

Reproduction

https://stackblitz.com/edit/sveltejs-kit-template-default-21ek1ezc?file=src%2Froutes%2F%2Bpage.svelte

The empty string can be seen when just submitting without inputting anything
Request Data:

Response:

Logs

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 20.19.1 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.8.2 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    @sveltejs/adapter-auto: ^6.0.0 => 6.1.0 
    @sveltejs/kit: 2.46.4 => 2.46.4 
    @sveltejs/vite-plugin-svelte: ^6.0.0 => 6.2.0 
    svelte: ^5.39.11 => 5.39.11 
    vite: ^7.0.4 => 7.1.5

Severity

annoyance

Additional Information

No response

[sillvva]

That is standard form behavior for empty text inputs. Svelte does not transform inputs other than checkbox to boolean and number to number.

[jere2101]

That means that v.optional() ( in valibots case ) is not a good option to use with remote forms, right ?

[sillvva]

Yeah for query and command optional is fine, because they receive an object directly. Forms still use standard HTML form submission behavior for the most part. If there is a field in your form, it will be submitted as a string in most cases. You'd use v.optional if the field is conditionally rendered in the UI and therefore conditionally present in the FormData.