io-ts-types/es6/fromNullable.js

A collection of codecs and combinators for use with io-ts

/**
 * @since 0.5.0
 */
import * as t from 'io-ts';
import { withValidate } from './withValidate';
/**
 * Returns a clone of the given codec that replace a nullable input with the given value `a`
 *
 * @example
 * import { fromNullable } from 'io-ts-types/es6/fromNullable'
 * import * as t from 'io-ts'
 * import { right } from 'fp-ts/es6/Either'
 * import { PathReporter } from 'io-ts/es6/PathReporter'
 *
 * const T = fromNullable(t.number, -1)
 *
 * assert.deepStrictEqual(T.decode(1), right(1))
 * assert.deepStrictEqual(T.decode(null), right(-1))
 * assert.deepStrictEqual(T.decode(undefined), right(-1))
 * assert.deepStrictEqual(PathReporter.report(T.decode('a')), ['Invalid value "a" supplied to : fromNullable(number)'])
 *
 * @since 0.5.0
 */
export function fromNullable(codec, a, name) {
    if (name === void 0) { name = "fromNullable(" + codec.name + ")"; }
    return withValidate(codec, function (u, c) { return (u == null ? t.success(a) : codec.validate(u, c)); }, name);
}