lazyAsync

Creates a lazy schema.

const Schema = v.lazyAsync<TWrapped>(getter);

Generics

• TWrapped extends BaseSchema<unknown, unknown, BaseIssue<unknown>> | BaseSchemaAsync<unknown, unknown, BaseIssue<unknown>>

Parameters

• getter (input: unknown) => MaybePromise<TWrapped>

Explanation

The getter function is called lazily to retrieve the schema. This is necessary to be able to access the input through the first argument of the getter function and to avoid a circular dependency for recursive schemas.

Returns

• Schema LazySchemaAsync<TWrapped>

Examples

The following examples show how lazyAsync can be used.

Transaction list schema

Recursive schema to validate transactions.

Due to a TypeScript limitation, the input and output types of recursive schemas cannot be inferred automatically. Therefore, you must explicitly specify these types using GenericSchemaAsync.

import { isTransactionValid } from '~/api';

type Transaction = {
  transactionId: string;
  next: Transaction | null;
};

const TransactionSchema: v.GenericSchemaAsync<Transaction> = v.objectAsync({
  transactionId: v.pipeAsync(
    v.string(),
    v.uuid(),
    v.checkAsync(isTransactionValid, 'The transaction is not valid.')
  ),
  next: v.nullableAsync(v.lazyAsync(() => TransactionSchema)),
});

Email or username schema

Schema to validate an object containing an email or username.

In most cases, unionAsync and variantAsync are the better choices for creating such a schema. I recommend using lazyAsync only in special cases.

import { isEmailPresent, isUsernamePresent } from '~/api';

const EmailOrUsernameSchema = v.lazyAsync((input) => {
  if (input && typeof input === 'object' && 'type' in input) {
    switch (input.type) {
      case 'email':
        return v.objectAsync({
          type: v.literal('email'),
          email: v.pipeAsync(
            v.string(),
            v.email(),
            v.checkAsync(
              isEmailPresent,
              'The email is not present in the database.'
            )
          ),
        });
      case 'username':
        return v.objectAsync({
          type: v.literal('username'),
          username: v.pipeAsync(
            v.string(),
            v.nonEmpty(),
            v.checkAsync(
              isUsernamePresent,
              'The username is not present in the database.'
            )
          ),
        });
    }
  }
  return v.never();
});

Related

The following APIs can be combined with lazyAsync.

Schemas

• any,
• array,
• bigint,
• blob,
• boolean,
• custom,
• date,
• enum,
• 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

Actions

• base64,
• bic,
• brand,
• bytes,
• check,
• checkItems,
• creditCard,
• cuid2,
• decimal,
• description,
• digits,
• email,
• emoji,
• empty,
• endsWith,
• everyItem,
• excludes,
• filterItems,
• findItem,
• finite,
• graphemes,
• hash,
• hexColor,
• hexadecimal,
• imei,
• includes,
• integer,
• ip,
• ipv4,
• ipv6,
• isoDate,
• isoDateTime,
• isoTime,
• isoTimeSecond,
• isoTimestamp,
• isoWeek,
• length,
• mac,
• mac48,
• mac64,
• mapItems,
• maxBytes,
• maxGraphemes,
• maxLength,
• maxSize,
• maxValue,
• maxWords,
• metadata,
• mimeType,
• minBytes,
• minGraphemes,
• minLength,
• minSize,
• minValue,
• minWords,
• multipleOf,
• nanoid,
• nonEmpty,
• notBytes,
• notGraphemes,
• notLength,
• notSize,
• notValue,
• notWords,
• octal,
• partialCheck,
• rawCheck,
• rawTransform,
• readonly,
• reduceItems,
• regex,
• safeInteger,
• size,
• someItem,
• sortItem,
• startsWith,
• title,
• toLowerCase,
• toMaxValue,
• toMinValue,
• toUpperCase,
• transform,
• trim,
• trimEnd,
• trimStart,
• ulid,
• url,
• uuid,
• value,
• words

Utils

• entriesFromList,
• isOfKind,
• isOfType

Async

• arrayAsync,
• checkAsync,
• customAsync,
• fallbackAsync,
• getDefaultsAsync,
• getFallbacksAsync,
• intersectAsync,
• 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,
• variantAsync