zod-validation

Zod Validation in Hono

Patterns for request validation using Zod and @hono/zod-validator.

Setup

bun add zod @hono/zod-validator

Basic Validation

JSON Body

import { zValidator } from '@hono/zod-validator'
import { z } from 'zod'

const createUserSchema = z.object({
  email: z.string().email('Invalid email address'),
  name: z.string().min(1, 'Name is required').max(100),
  age: z.number().int().positive().optional(),
})

app.post('/users',
  zValidator('json', createUserSchema),
  async (c) => {
    const data = c.req.valid('json')
    // data is typed as { email: string; name: string; age?: number }
    return c.json(data, 201)
  }
)

Query Parameters

const paginationSchema = z.object({
  page: z.coerce.number().int().positive().default(1),
  limit: z.coerce.number().int().min(1).max(100).default(20),
  sort: z.enum(['asc', 'desc']).default('desc'),
  search: z.string().optional(),
})

app.get('/users',
  zValidator('query', paginationSchema),
  async (c) => {
    const { page, limit, sort, search } = c.req.valid('query')
    // All values are properly typed and coerced
    return c.json({ page, limit, sort, search })
  }
)

Path Parameters

const userParamsSchema = z.object({
  id: z.string().uuid('Invalid user ID format'),
})

app.get('/users/:id',
  zValidator('param', userParamsSchema),
  async (c) => {
    const { id } = c.req.valid('param')
    return c.json({ id })
  }
)

Headers

const authHeaderSchema = z.object({
  authorization: z.string().startsWith('Bearer '),
  'x-request-id': z.string().uuid().optional(),
})

app.get('/protected',
  zValidator('header', authHeaderSchema),
  async (c) => {
    const headers = c.req.valid('header')
    return c.json({ authenticated: true })
  }
)

Form Data

const uploadSchema = z.object({
  title: z.string().min(1),
  description: z.string().optional(),
  // File validation happens separately
})

app.post('/upload',
  zValidator('form', uploadSchema),
  async (c) => {
    const { title, description } = c.req.valid('form')
    return c.json({ title, description })
  }
)