exactOptionalAsync

Creates an exact optional schema.

const Schema = v.exactOptionalAsync<TWrapped, TDefault>(wrapped, default_);

Generics

• TWrapped extends BaseSchema<unknown, unknown, BaseIssue<unknown>> | BaseSchemaAsync<unknown, unknown, BaseIssue<unknown>>
• TDefault extends DefaultAsync<TWrapped, never>

Parameters

• wrapped TWrapped
• default_ TDefault

Explanation

With exactOptionalAsync the validation of your schema will pass missing object entries, and if you specify a default_ input value, the schema will use it if the object entry is missing. For this reason, the output type may differ from the input type of the schema.

Important: When used in object schemas, if a key is missing and no default_ value is provided, the schema's pipe (including transformations) will not be executed. To ensure pipes run for missing keys, provide a default_ value.

The difference to optionalAsync is that this schema function follows the implementation of TypeScript's exactOptionalPropertyTypes configuration and only allows missing but not undefined object entries.

Returns

• Schema ExactOptionalSchemaAsync<TWrapped, TDefault>

Examples

The following examples show how exactOptionalAsync can be used.

New user schema

Schema to validate new user details.

import { isEmailUnique, isUsernameUnique } from '~/api';

const NewUserSchema = v.objectAsync({
  email: v.pipeAsync(
    v.string(),
    v.email(),
    v.checkAsync(isEmailUnique, 'The email is not unique.')
  ),
  username: v.exactOptionalAsync(
    v.pipeAsync(
      v.string(),
      v.nonEmpty(),
      v.checkAsync(isUsernameUnique, 'The username is not unique.')
    )
  ),
  password: v.pipe(v.string(), v.minLength(8)),
});

/*
  The input and output types of the schema:
    {
      email: string;
      password: string;
      username?: string;
    }
*/

Unwrap exact optional schema

Use unwrap to undo the effect of exactOptionalAsync.

import { isUsernameUnique } from '~/api';

const UsernameSchema = v.unwrap(
  // Assume this schema is from a different file and is reused here
  v.exactOptionalAsync(
    v.pipeAsync(
      v.string(),
      v.nonEmpty(),
      v.checkAsync(isUsernameUnique, 'The username is not unique.')
    )
  )
);

Exact optional async with pipes

When using exactOptionalAsync in a pipeAsync, the pipe actions only execute if a default_ value is provided or the key is present. This applies to all pipe actions including transformAsync, checkAsync, and others.

const SchemaWithoutDefault = v.objectAsync({
  isEnabled: v.pipeAsync(
    v.exactOptionalAsync(v.string()),
    v.transformAsync(async (value) => value === '1') // Does not run for missing keys
  ),
}); // Output type: { isEnabled?: boolean }

const SchemaWithDefault = v.objectAsync({
  isEnabled: v.pipeAsync(
    v.exactOptionalAsync(v.string(), '0'), // Default value provided
    v.transformAsync(async (value) => value === '1') // Runs for missing keys too
  ),
}); // Output type: { isEnabled: boolean }

Related

The following APIs can be combined with exactOptionalAsync.

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

• config,
• getDefault,
• getFallback,
• unwrap

Actions

• brand,
• check,
• description,
• flavor,
• guard,
• metadata,
• partialCheck,
• rawCheck,
• rawTransform,
• readonly,
• title,
• transform

Utils

• entriesFromList,
• isOfKind,
• isOfType

Async

• arrayAsync,
• awaitAsync,
• checkAsync,
• customAsync,
• 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,
• undefinedableAsync,
• unionAsync,
• variantAsync