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Runtime validation with ArkType

Use case​

Validate API responses at runtime using ArkType, a TypeScript-native validator.

Smallest working example​

import { createClient } from '@parcely/core'
import { type } from 'arktype'

const http = createClient({ baseURL: 'https://api.example.com' })

const User = type({
  id: 'string',
  name: 'string',
  email: 'string',
})

const { data } = await http.get('/users/me', {
  validate: User,
})

How it works​

ArkType 2+ implements Standard Schema v1, so it works with parcely's validate option out of the box.

Error handling​

import { isHttpError } from '@parcely/core'

try {
  await http.get('/users/me', { validate: User })
} catch (err) {
  if (isHttpError(err) && err.code === 'ERR_VALIDATION') {
    console.log('Validation failed:', err.cause)
  }
}

Axios equivalent​

Axios has no built-in validation support.

Notes and gotchas​

  • ArkType is a dependency of your app, not of parcely.
  • ArkType 2+ is required for Standard Schema v1 support.
  • The Validator<T> type supports Standard Schema v1, .parse() objects, and plain functions.