getDefaults returns undefined for optional with a default of empty string or false

[dboune]

Problem

getDefaults returns undefined for an optional with a default set to an empty string or false. I believe it should return the value supplied.

Note: This same issue applies to getFallbacks with fallback. In all cases, parse does the right thing.

Example:

import { object, optional, string, getDefaults } from 'valibot';

const Schema = object({
  field: optional(string(), ''),
});

const schemaDefaults = getDefaults(Schema)

console.log(schemaDefaults);

I believe the reason for the current behavior may be here:
https://github.com/fabian-hiller/valibot/blob/6578c3304062e6c2e5cb14fc0f4d6dbb1e6eaffb/library/src/methods/getDefaults/getDefaults.ts#L34C3-L34C24

Rationale

I'm currently evaluating a move from TypeBox to Valibot for form validation because dealing with the validation of unions in TypeBox is complex, and potentially maintaining two schemas for input and output is undesirable. We use Value.Create(Schema) to obtain the initial state of our form from our "single source of truth" about the shape of the form state object. I was attempting to re-create this with Valibot.

In React + MUI, we cannot (or should not) set the initial value of our form fields to undefined unless we intend to operate them uncontrolled, which is discouraged.

Workaround

Using a function to supply the default value renders the desired result.

import { object, optional, string, getDefaults } from 'valibot';

const Schema = object({
  field: optional(string(), () => ''),
});

const schemaDefaults = getDefaults(Schema)

console.log(schemaDefaults);

Misc

Valibot looks very nice overall. Thank you!

[fabian-hiller]

Thanks for reporting this bug. I will change the if-statement to schema.default !== undefined and release this change with the next version. Until then, a function can be used as a workaround when passing empty strings.

[fabian-hiller]

v0.26.0 is available