typescript-string-enums with iots

typescript-string-enums_iots.ts

import * as t from 'io-ts'
export class FromTsStringEnumType<T extends object> extends t.Type<T[keyof T]> {
  constructor (public enumObject: T, name?: string) {
    super(
      name || `fromTsStringEnum: ${enumObject}`,
      (u): u is T[keyof T] => Object
                                .values(enumObject)
                                .some(v => v === u),
      (u, c) => (this.is(u) ? t.success(u) : t.failure(u, c)),
      t.identity,
    )
  }
}

export function fromTsStringEnum<T extends object> (
  enumObject: T,
  name?: string,
): FromTsStringEnumType<T> {
  return new FromTsStringEnumType(enumObject, name)
}

///////// USAGE EXAMPLE: /////////
import { Enum as tseEnum } from 'typescript-string-enums'

const arrEnum = tseEnum(
  'a', 'b',
)

type arrEnum = tseEnum<typeof arrEnum>


const test = t.type({
  enum: fromTsStringEnum(arrEnum),
})

type test = t.TypeOf<typeof test>

const validateOK1 = test
  .decode({
    enum: 'c',
  })
  .isLeft()

console.log('validateOK1', validateOK1)

const validateOK2 = test
  .decode({
    enum: arrEnum.b,
  })
  .isLeft()

console.log('validateOK2', validateOK2)

function testaaa (a: test) {
  if (a.enum === arrEnum.a) {
    return false
  }

  return true
}