# ulid

> This document is the Markdown version of [valibot.dev/api/ulid/](https://valibot.dev/api/ulid/). For the complete documentation index, see [llms.txt](https://valibot.dev/llms.txt).

Creates an [ULID](https://github.com/ulid/spec) validation action.

```ts
const Action = v.ulid<TInput, TMessage>(message);
```

## Generics

- `TInput` `extends string`
- `TMessage` `extends ErrorMessage<UlidIssue<TInput>> | undefined`

## Parameters

- `message` `TMessage`

### Explanation

With `ulid` you can validate the formatting of a string. If the input is not an ULID, you can use `message` to customize the error message.

## Returns

- `Action` `UlidAction<TInput, TMessage>`

## Examples

The following examples show how `ulid` can be used.

### ULID schema

Schema to validate an ULID.

```ts
const UlidSchema = v.pipe(v.string(), v.ulid('The ULID is badly formatted.'));
```

## Related

The following APIs can be combined with `ulid`.

### Schemas

[`any`](/api/any.md), [`custom`](/api/custom.md), [`string`](/api/string.md)

### Methods

[`pipe`](/api/pipe.md)

### Utils

[`isOfKind`](/api/isOfKind.md), [`isOfType`](/api/isOfType.md)