fallback

Returns a fallback value as output if the input does not match the schema.

const Schema = v.fallback<TSchema, TFallback>(schema, fallback);

Generics

• TSchema extends BaseSchema<unknown, unknown, BaseIssue<unknown>>
• TFallback extends Fallback<TSchema>

Parameters

• schema TSchema
• fallback TFallback

Explanation

fallback allows you to define a fallback value for the output that will be used if the validation of the input fails. This means that no issues will be returned when using fallback and the schema will always return an output.

If you only want to set a default value for null or undefined inputs, you should use optional, nullable or nullish instead.

The fallback value is not validated. Make sure that the fallback value matches your schema.

Returns

• Schema SchemaWithFallback<TSchema, TFallback>

Examples

The following examples show how fallback can be used.

Fallback string schema

Schema that will always return a string output.

const FallbackStringSchema = v.fallback(v.string(), "I'm the fallback!");

Fallback date schema

Schema that will always return a Date output.

By using a function as the fallback parameter, the schema will return a new Date instance each time the input does not match the schema.

const FallbackDateSchema = v.fallback(v.date(), () => new Date());

Related

The following APIs can be combined with fallback.

Schemas

any, array, bigint, blob, boolean, custom, date, enum, exactOptional, file, function, instance, intersect, lazy, literal, looseObject, looseTuple, map, nan, never, nonNullable, nonNullish, nonOptional, null, nullable, nullish, number, object, objectWithRest, optional, picklist, promise, record, set, strictObject, strictTuple, string, symbol, tuple, tupleWithRest, undefined, undefinedable, union, unknown, variant, void

Methods

assert, config, getDefault, getDefaults, getFallback, getFallbacks, is, keyof, message, omit, parse, parser, partial, pick, pipe, required, safeParse, safeParser, unwrap

Actions

args, base64, bic, 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

isOfKind, isOfType