Validator Middleware for Hono

Validator middleware for Hono. This middleware that wraps validator.js validates form body, queries, headers, and JSON body.

IT’S BETA QUALITY. DO NOT USE IT FOR PRODUCTION USAGE.

Install

npm:

npm install hono
npm install @honojs/validator

Deno:

import { serve } from 'https://deno.land/std/http/server.ts'
import { Hono } from 'https://deno.land/x/hono/mod.ts'
import { validation } from 'https://deno.land/x/hono_validator/mod.ts'

//...
serve(app.fetch)

Usage

Synopsis

import { Hono } from 'hono'
import { validation } from '@honojs/validator'

const app = new Hono()

app.post(
  '/post',
  validation((v, message) => ({
    body: {
      title: [v.required, message('Title is required!!')],
      body: [v.isLength, { max: 400 }],
    },
  })),
  (c) => c.text('Created!', 201)
)

export default app

Validation Rules

Validator Middleware wraps validator.js. There are a lot of rules in the library. You can validate four types of targets: form body, request headers, search params, and JSON body.

app.post(
  '*',
  validation((v) => ({
    body: {
      // Pass the parameters to the validator using array:
      name: [v.isAlpha, [v.contains, 'abc']],
    },
    header: {
      'x-custom-header': v.isAlphanumeric,
    },
    query: {
      q: v.required,
    },
    json: {
      // You can specify the key using JSON Path:
      'post.author.email': [v.required, v.isEmail],
    },
  }))
)

Sanitization

You can sanitize the values before passing the theme to the validator.

app.post(
  '/post',
  validation((v) => ({
    body: {
      email: [v.trim, v.isEmail],
    },
  }))
)

Error Handling

If it’s invalid, it will return “400” response with the messages set automatically.

Custom Message

You can set custom error messages for each rule.

app.post(
  '/post',
  validation((v, message) => ({
    body: {
      title: [v.required, message('Please set the title! Please!')],
    },
  }))
)

Custom Validator

Making custom validator is easy.

const passwordValidator = (value: string) => {
  return value.match(/[a-zA-Z0-9+=]+/) ? true : false
}

app.post(
  '/custom-validator',
  validation((_, message) => ({
    body: {
      password: [passwordValidator, message('password is wrong')],
    },
  }))
)

Validation Results

You can handle the errors more flexibly using done method.

app.get(
  '/custom-error',
  validation((v) => ({
    body: {
      userId: v.required,
    },
    done: (result, c) => {
      if (result.hasError) {
        return c.json({ messages: result.messages }, 403)
      }
    },
  })),
  (c) => {
    return c.json({ messages: ['SUCCESS'] })
  }
)

Author

Yusuke Wada https://github.com/yusukebe

License

MIT