optional

Creates an optional schema.

const Schema = optional<TWrapped, TDefault>(wrapped, default_);

Generics

• TWrapped extends BaseSchema
• TDefault extends Default<TWrapped>

Parameters

• wrapped TWrapped
• default_ TDefault

Explanation

With optional the validation of your schema will pass undefined inputs, and if you specify a default_ input value, the schema will use it if the input is undefined. For this reason, the output type may differ from the input type of the schema.

Note that optional does not accept null as an input. If you want to accept null inputs, use nullable, and if you want to accept null and undefined inputs, use nullish instead. Also, if you want to set a default output value for any invalid input, you should use fallback instead.

Returns

• Schema OptionalSchema<TWrapped, TDefault>

Examples

The following examples show how optional can be used.

Optional string schema

Schema that accepts string and undefined.

const OptionalStringSchema = optional(string(), "I'm the default!");

Optional date schema

Schema that accepts Date and undefined.

By using a function as the default_ parameter, the schema will return a new Date instance each time the input is undefined.

const OptionalDateSchema = optional(date(), () => new Date());

Optional entry schema

Object schema with an optional entry.

const OptionalEntrySchema = object({
  key: optional(string()),
});

Unwrap optional schema

Use unwrap to undo the effect of optional.

const OptionalNumberSchema = optional(number());
const NumberSchema = unwrap(OptionalNumberSchema);

Related

The following APIs can be combined with optional.

Schemas

• any,
• array,
• bigint,
• blob,
• boolean,
• date,
• enum_,
• instance,
• intersect,
• lazy,
• literal,
• map,
• nan,
• never,
• nonNullable,
• nonNullish,
• nonOptional,
• null_,
• nullable,
• nullish,
• number,
• object,
• picklist,
• record,
• set,
• special,
• string,
• symbol,
• tuple,
• undefined_,
• union,
• unknown,
• variant,
• void_

Methods

• brand,
• coerce,
• fallback,
• getDefault,
• getDefaults,
• getFallback,
• getFallbacks,
• is,
• parse,
• safeParse,
• transform,
• unwrap