Add stringbool feature similar to Zod #1240
Description
Proposal
Add stringbool to Valibot core
Intro
Zod added a new schema in v4 z. stringbool() (https://zod.dev/api?id=stringbool)
In some cases (e.g. parsing environment variables) it's valuable to parse certain string "boolish" values to a plain boolean value. To support this, Zod 4 introduces z.stringbool():
This works great when validating and parsing environment variables (e.g. using t3-env), where we want a specific set of string values to be converted into a boolean.
Usage example with Zod and t3-env
src/evn.ts
import { createEnv } from "@t3-oss/env-core";
import { z } from "zod/v4";
export const env = createEnv({
server: {
DATABASE_URL: z.string().url(),
DATABASE_LOG_ENABLED: z.stringbool(),
},
runtimeEnv: process.env,
});.env
DATABASE_URL="https://sometihng.com"
DATABASE_LOG_ENABLED="1"src/main.ts
import { env } from './src/env';
env.DATABASE_LOG_ENABLED
// trueBasic user-land implementation of stringbool in Valibot
src/env.ts
import { optional, picklist, pipe, string, transform, url } from 'valibot';
import { createEnv } from '@t3-oss/env-nextjs';
interface StringBoolParams {
truthy?: string[];
falsy?: string[];
case?: 'sensitive' | 'insensitive' | undefined;
}
function stringbool(params: StringBoolParams = {}) {
const defaultValues = {
truthy: ['true', '1', 'yes', 'on', 'y', 'enabled'] as const,
falsy: ['false', '0', 'no', 'off', 'n', 'disabled'] as const,
};
const truthy = params.truthy ?? defaultValues.truthy;
const falsy = params.falsy ?? defaultValues.falsy;
const stringBoolEnum = [...truthy, ...falsy] as const;
return pipe(
string(),
transform((str) => (params.case === 'sensitive' ? str : str.toLowerCase())),
picklist(stringBoolEnum),
transform((str) => truthy.includes(str)),
);
}
export const env = createEnv({
server: {
DATABASE_URL: pipe(string(), url()),
DATABASE_LOG_ENABLED: optional(stringbool(), 'false'),
},
runtimeEnv: process.env,
});Considerations
Should it be added to Valibot core or as an external utility library?
- I believe it should be in core as it is a common enough use case to be useful out-of-the-box
Should it be a Schema or an Action?
- Reading through Valibot Docs - Mental model, it seems that
stringboolin Valibot should be an Action and not a Schema, as it basically accepts only a string as an input and transforms the result into a boolean based on the value
Implementation
- As mentioned on Discord, the implementation should not use other schemas or methods, but serve as standalone code with no dependencies
- Can check for current implementation of coercion actions for primitives
Related
- Similar actions can be proposed:
truthyandfalsy