customAsync

Creates a custom schema.

This schema function allows you to define a schema that matches a value based on a custom function. Use it whenever you need to define a schema that cannot be expressed using any of the other schema functions.

const Schema = v.customAsync<TInput, TMessage>(check, message);

Generics

• TInput extends any
• TMessage extends ErrorMessage<CustomIssue> | undefined = ErrorMessage<CustomIssue> | undefined

Parameters

• check (input: unknown) => MaybePromise<boolean>
• message TMessage

Explanation

With customAsync you can validate the data type of the input. If the input does not match the validation of check, you can use message to customize the error message.

Make sure that the validation in check matches the data type of TInput.

Returns

• Schema CustomSchemaAsync<TInput, TMessage>

Examples

The following examples show how customAsync can be used.

Vacant seat schema

Schema to validate a vacant seat.

import { isSeatVacant } from '~/api';

type Group = 'A' | 'B' | 'C' | 'D' | 'E';
type DigitLessThanSix = '0' | '1' | '2' | '3' | '4' | '5';
type Digit = DigitLessThanSix | '6' | '7' | '8' | '9';
type Seat = `${Group}${DigitLessThanSix}${Digit}`;

function isSeat(possibleSeat: string): possibleSeat is Seat {
  return /^[A-E][0-5]\d$/.test(possibleSeat);
}

const VacantSeatSchema = v.customAsync<Seat>(
  (input) => typeof input === 'string' && isSeat(input) && isSeatVacant(input),
  'The input is not a valid vacant seat.'
);

Related

The following APIs can be combined with customAsync.

Schemas

array, exactOptional, intersect, lazy, looseObject, looseTuple, map, nonNullable, nonNullish, nonOptional, nullable, nullish, object, objectWithRest, optional, record, set, strictObject, strictTuple, tuple, tupleWithRest, undefinedable, union

Methods

config, getDefault, getFallback

Actions

args, base64, brand, bytes, check, checkItems, codePoints, creditCard, cuid2, decimal, description, digits, domain, email, emoji, empty, endsWith, entries, everyItem, excludes, filterItems, findItem, finite, flavor, graphemes, gtValue, guard, hash, hexadecimal, hexColor, imei, includes, integer, ip, ipv4, ipv6, isbn, isrc, isoDate, isoDateTime, isoDateTimeSecond, isoTime, isoTimeSecond, isoTimestamp, isoWeek, ksuid, length, ltValue, mac, mac48, mac64, mapItems, maxBytes, maxCodePoints, maxEntries, maxGraphemes, maxLength, maxSize, maxValue, maxWords, metadata, mimeType, minBytes, minCodePoints, minEntries, minGraphemes, minLength, minSize, minValue, minWords, multipleOf, nanoid, nonEmpty, notBytes, notCodePoints, notEntries, notGraphemes, notLength, notSize, notValue, notValues, notWords, octal, parseJson, partialCheck, rawCheck, rawTransform, readonly, reduceItems, regex, returns, rfcEmail, safeInteger, size, slug, someItem, sortItems, startsWith, stringifyJson, title, toCamelCase, toKebabCase, toLowerCase, toMaxValue, toMinValue, toPascalCase, toSnakeCase, toUpperCase, transform, trim, trimEnd, trimStart, ulid, url, uuid, value, values, words

Utils

entriesFromList, isOfKind, isOfType

Async

arrayAsync, awaitAsync, checkAsync, exactOptionalAsync, fallbackAsync, getDefaultsAsync, getFallbacksAsync, intersectAsync, lazyAsync, looseObjectAsync, looseTupleAsync, mapAsync, nonNullableAsync, nonNullishAsync, nonOptionalAsync, nullableAsync, nullishAsync, objectAsync, objectWithRestAsync, optionalAsync, parseAsync, parserAsync, partialCheckAsync, pipeAsync, rawCheckAsync, rawTransformAsync, recordAsync, safeParseAsync, safeParserAsync, setAsync, strictObjectAsync, strictTupleAsync, transformAsync, tupleAsync, tupleWithRestAsync, unionAsync