zMapKeys.ts

zMapKeys.ts

// Type inference does not work yet
export function zMapKeys<
  Shape extends z.ZodRawShape,
  T extends z.ZodObject<Shape>,
  Key extends keyof Shape,
  MapFn extends <T extends Key>(v: Shape[T], k: T) => PropertyKey,
>(schema: T, renameMap: Record<Key, PropertyKey | MapFn>) {
  const keys = Object.keys(schema.shape) as Key[]
  return schema.transform((input) => {
    let output: Record<PropertyKey, any> = {}
    for (const k of keys) {
      let targetKey: PropertyKey = k as PropertyKey
      if (typeof renameMap[k] === 'function') {
        targetKey = (renameMap[k] as MapFn)(input[k]!, k)
      }
      if (typeof renameMap[k] === 'string') {
        targetKey = renameMap[k] as PropertyKey
      }
      output[targetKey]
    }
    return output
  })
}

const out = zMapKeys(z.object({ a: z.string(), b: z.string() }), { b: 'c' })