Encode a custom type on requests

A field can travel as an ISO string and be a Temporal.PlainTime in your code. Responses decode, requests encode.

Printer node handlers read this.options.direction: 'decode' for response schemas, 'encode' for request bodies and parameters.

kubb.config.ts

import { defineConfig } from 'kubb/config'
import { pluginZod } from '@kubb/plugin-zod'
import type { PrinterZodNodes } from '@kubb/plugin-zod'

const nodes: PrinterZodNodes = {
  time() {
    return this.options.direction === 'encode'
      ? 'z.instanceof(Temporal.PlainTime).transform((value) => value.toString())'
      : 'z.iso.time().transform((value) => Temporal.PlainTime.from(value))'
  },
}

export default defineConfig({
  input: './petStore.yaml',
  output: { path: './src/gen', clean: true },
  plugins: [
    pluginZod({
      output: { path: 'zod', mode: 'directory' },
      printer: { nodes },
    }),
  ],
})

Override the time node, not string. An OpenAPI format: 'time' field parses to a time node, so a string handler never sees it. The same holds for date and date-time, which parse to date and datetime nodes.

Decode from z.iso.time(), not a bare z.string(). An unchecked string reaching Temporal.PlainTime.from throws a RangeError out of the transform, instead of surfacing as the ParseError a client validator raises.

Output example

A component carrying the type is emitted twice, and a $ref request body resolves to the input one:

src/gen/zod/slotSchema.ts

export const slotSchema = z.object({
  startsAt: z.iso.time().transform((value) => Temporal.PlainTime.from(value)),
})

export const slotInputSchema = z.object({
  startsAt: z.instanceof(Temporal.PlainTime).transform((value) => value.toString()),
})

src/gen/zod/bookSlotSchema.ts

export const bookSlotStatus201Schema = slotSchema      // decode
export const bookSlotBodySchema = slotInputSchema      // encode

Limits

The generated types describe the wire shape

If the client is also typed by @kubb/plugin-ts, its request and response types come from the spec, so a format: 'time' field is typed string there whatever the Zod schema converts it to at runtime. Drop pluginTs and add inferred: true on pluginZod instead, and pluginFetch or pluginAxios types the operation from z.infer on this schema, which follows the conversion.

Built-in date conversion

Dates already work this way with no configuration. Set dateType: 'date' on the adapter and a date-time field decodes to a Date on responses and encodes back to an ISO string on requests, through a $ref too:

src/gen/zod/orderSchema.ts

export const orderSchema = z.object({
  shipDate: z.iso.datetime().transform((value) => new Date(value)).optional(),
})

export const orderInputSchema = z.object({
  shipDate: z.date().transform((value) => value.toISOString()).optional(),
})

The built-in date handler branches on direction exactly like a custom one. Overriding printer.nodes.date replaces it whole, that branch included.