Namespace Mapper

A module for defining functional schemas to map between different types. This module is useful for parsing to or from JSON/protobufs to domain types.

Mappers support greedy validation, so all validation errors are aggregated and reported vs failing on the first invalid input.

Example

import { Mapper as M } from '@vertexvis/utils';

interface Address {
  address: string;
  city: string;
  state: string;
  zip: string;
}

interface Person {
  name: string;
  addresses: Address[];
}

type AddressJson = Partial<Address>;
type PersonJson = {
  name?: string;
  addresses?: AddressJson[];
}

const mapAddress: M.Func<AddressJson, Address> = M.defineMapper(
  M.read(
    M.requireProp('address'),
    M.requireProp('city'),
    M.requireProp('state'),
    M.requireProp('zip')
  ),
  ([address, city, state, zip]) => ({
    address, city, state, zip
  })
);

const mapPerson: M.Func<PersonJson, Person> = M.defineMapper(
  M.read(
    M.requireProp('name'),
    M.mapProp(
      'addresses',
      M.compose(M.required('addresses'), M.mapArray(mapAddress))
    )
  ),
  ([name, addresses]) => ({ name, addresses })
);

const person = mapPerson({
  name: 'John',
  addresses: [{ address: '123', city: 'Ames', state: 'IA', zip: '50010' }]
});

const invalidPerson = mapPerson({
  addresses: [{ city: 'Ames', state: 'IA', zip: '50010' }]
});